_ Git - rust-lightning/blob - lightning/src/routing/router.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use std::cmp;
  25 use std::collections::{HashMap, BinaryHeap};
  26 use std::ops::Deref;
  27
  28 /// A hop in a route
  29 #[derive(Clone, PartialEq)]
  30 pub struct RouteHop {
  31         /// The node_id of the node at this hop.
  32         pub pubkey: PublicKey,
  33         /// The node_announcement features of the node at this hop. For the last hop, these may be
  34         /// amended to match the features present in the invoice this node generated.
  35         pub node_features: NodeFeatures,
  36         /// The channel that should be used from the previous hop to reach this node.
  37         pub short_channel_id: u64,
  38         /// The channel_announcement features of the channel that should be used from the previous hop
  39         /// to reach this node.
  40         pub channel_features: ChannelFeatures,
  41         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  42         /// For the last hop, this should be the full value of the payment (might be more than
  43         /// requested if we had to match htlc_minimum_msat).
  44         pub fee_msat: u64,
  45         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  46         /// expected at the destination, in excess of the current block height.
  47         pub cltv_expiry_delta: u32,
  48 }
  49
  50 /// (C-not exported)
  51 impl Writeable for Vec<RouteHop> {
  52         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  53                 (self.len() as u8).write(writer)?;
  54                 for hop in self.iter() {
  55                         hop.pubkey.write(writer)?;
  56                         hop.node_features.write(writer)?;
  57                         hop.short_channel_id.write(writer)?;
  58                         hop.channel_features.write(writer)?;
  59                         hop.fee_msat.write(writer)?;
  60                         hop.cltv_expiry_delta.write(writer)?;
  61                 }
  62                 Ok(())
  63         }
  64 }
  65
  66 /// (C-not exported)
  67 impl Readable for Vec<RouteHop> {
  68         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Vec<RouteHop>, DecodeError> {
  69                 let hops_count: u8 = Readable::read(reader)?;
  70                 let mut hops = Vec::with_capacity(hops_count as usize);
  71                 for _ in 0..hops_count {
  72                         hops.push(RouteHop {
  73                                 pubkey: Readable::read(reader)?,
  74                                 node_features: Readable::read(reader)?,
  75                                 short_channel_id: Readable::read(reader)?,
  76                                 channel_features: Readable::read(reader)?,
  77                                 fee_msat: Readable::read(reader)?,
  78                                 cltv_expiry_delta: Readable::read(reader)?,
  79                         });
  80                 }
  81                 Ok(hops)
  82         }
  83 }
  84
  85 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  86 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  87 #[derive(Clone, PartialEq)]
  88 pub struct Route {
  89         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  90         /// last RouteHop in each path must be the same.
  91         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  92         /// destination. Thus, this must always be at least length one. While the maximum length of any
  93         /// given path is variable, keeping the length of any path to less than 20 should currently
  94         /// ensure it is viable.
  95         pub paths: Vec<Vec<RouteHop>>,
  96 }
  97
  98 impl Writeable for Route {
  99         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 100                 (self.paths.len() as u64).write(writer)?;
 101                 for hops in self.paths.iter() {
 102                         hops.write(writer)?;
 103                 }
 104                 Ok(())
 105         }
 106 }
 107
 108 impl Readable for Route {
 109         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 110                 let path_count: u64 = Readable::read(reader)?;
 111                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 112                 for _ in 0..path_count {
 113                         paths.push(Readable::read(reader)?);
 114                 }
 115                 Ok(Route { paths })
 116         }
 117 }
 118
 119 /// A channel descriptor which provides a last-hop route to get_route
 120 #[derive(Clone)]
 121 pub struct RouteHint {
 122         /// The node_id of the non-target end of the route
 123         pub src_node_id: PublicKey,
 124         /// The short_channel_id of this channel
 125         pub short_channel_id: u64,
 126         /// The fees which must be paid to use this channel
 127         pub fees: RoutingFees,
 128         /// The difference in CLTV values between this node and the next node.
 129         pub cltv_expiry_delta: u16,
 130         /// The minimum value, in msat, which must be relayed to the next hop.
 131         pub htlc_minimum_msat: Option<u64>,
 132         /// The maximum value in msat available for routing with a single HTLC.
 133         pub htlc_maximum_msat: Option<u64>,
 134 }
 135
 136 #[derive(Eq, PartialEq)]
 137 struct RouteGraphNode {
 138         pubkey: PublicKey,
 139         lowest_fee_to_peer_through_node: u64,
 140         lowest_fee_to_node: u64,
 141         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 142         // This value is upper-bounded by us by:
 143         // - how much is needed for a path being constructed
 144         // - how much value can channels following this node (up to the destination) can contribute,
 145         //   considering their capacity and fees
 146         value_contribution_msat: u64,
 147         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 148         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 149         path_htlc_minimum_msat: u64,
 150 }
 151
 152 impl cmp::Ord for RouteGraphNode {
 153         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 154                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 155                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 156                 other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 157         }
 158 }
 159
 160 impl cmp::PartialOrd for RouteGraphNode {
 161         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 162                 Some(self.cmp(other))
 163         }
 164 }
 165
 166 struct DummyDirectionalChannelInfo {
 167         cltv_expiry_delta: u32,
 168         htlc_minimum_msat: u64,
 169         htlc_maximum_msat: Option<u64>,
 170         fees: RoutingFees,
 171 }
 172
 173 /// It's useful to keep track of the hops associated with the fees required to use them,
 174 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 175 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 176 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 177 #[derive(Clone)]
 178 struct PathBuildingHop<'a> {
 179         // The RouteHint fields which will eventually be used if this hop is used in a final Route.
 180         // Note that node_features is calculated separately after our initial graph walk.
 181         pubkey: PublicKey,
 182         short_channel_id: u64,
 183         channel_features: &'a ChannelFeatures,
 184         fee_msat: u64,
 185         cltv_expiry_delta: u32,
 186
 187         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 188         src_lowest_inbound_fees: RoutingFees,
 189         /// Fees of the channel used in this hop.
 190         channel_fees: RoutingFees,
 191         /// All the fees paid *after* this channel on the way to the destination
 192         next_hops_fee_msat: u64,
 193         /// Fee paid for the use of the current channel (see channel_fees).
 194         /// The value will be actually deducted from the counterparty balance on the previous link.
 195         hop_use_fee_msat: u64,
 196         /// Used to compare channels when choosing the for routing.
 197         /// Includes paying for the use of a hop and the following hops, as well as
 198         /// an estimated cost of reaching this hop.
 199         /// Might get stale when fees are recomputed. Primarily for internal use.
 200         total_fee_msat: u64,
 201         /// This is useful for update_value_and_recompute_fees to make sure
 202         /// we don't fall below the minimum. Should not be updated manually and
 203         /// generally should not be accessed.
 204         htlc_minimum_msat: u64,
 205         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 206         /// walk and may be invalid thereafter.
 207         path_htlc_minimum_msat: u64,
 208         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 209         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 210         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 211         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 212         /// avoid processing them again.
 213         was_processed: bool,
 214         #[cfg(any(test, feature = "fuzztarget"))]
 215         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 216         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 217         // value_contribution_msat, which requires tracking it here. See comments below where it is
 218         // used for more info.
 219         value_contribution_msat: u64,
 220 }
 221
 222 // Instantiated with a list of hops with correct data in them collected during path finding,
 223 // an instance of this struct should be further modified only via given methods.
 224 #[derive(Clone)]
 225 struct PaymentPath<'a> {
 226         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 227 }
 228
 229 impl<'a> PaymentPath<'a> {
 230         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 231         fn get_value_msat(&self) -> u64 {
 232                 self.hops.last().unwrap().0.fee_msat
 233         }
 234
 235         fn get_total_fee_paid_msat(&self) -> u64 {
 236                 if self.hops.len() < 1 {
 237                         return 0;
 238                 }
 239                 let mut result = 0;
 240                 // Can't use next_hops_fee_msat because it gets outdated.
 241                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 242                         if i != self.hops.len() - 1 {
 243                                 result += hop.fee_msat;
 244                         }
 245                 }
 246                 return result;
 247         }
 248
 249         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 250         // to change fees may result in an inconsistency.
 251         //
 252         // Sometimes we call this function right after constructing a path which has inconsistent
 253         // (in terms of reaching htlc_minimum_msat), so that this function puts the fees in order.
 254         // In that case we call it on the "same" amount we initially allocated for this path, and which
 255         // could have been reduced on the way. In that case, there is also a risk of exceeding
 256         // available_liquidity inside this function, because the function is unaware of this bound.
 257         // In our specific recomputation cases where we never increase the value the risk is pretty low.
 258         // This function, however, does not support arbitrarily increasing the value being transferred,
 259         // and the exception will be triggered.
 260         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 261                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 262
 263                 let mut total_fee_paid_msat = 0 as u64;
 264                 for i in (0..self.hops.len()).rev() {
 265                         let last_hop = i == self.hops.len() - 1;
 266
 267                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 268                         // will consist of the fees for the use of the next hop, and extra fees to match
 269                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 270                         let mut cur_hop_fees_msat = 0;
 271                         if !last_hop {
 272                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 273                         }
 274
 275                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 276                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 277                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 278                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 279                         // set it too high just to maliciously take more fees by exploiting this
 280                         // match htlc_minimum_msat logic.
 281                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 282                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 283                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 284                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 285                                 //
 286                                 // This might make us end up with a broken route, although this should be super-rare
 287                                 // in practice, both because of how healthy channels look like, and how we pick
 288                                 // channels in add_entry.
 289                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 290                                 // all payments*.
 291                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 292                                 total_fee_paid_msat += extra_fees_msat;
 293                                 cur_hop_fees_msat += extra_fees_msat;
 294                         }
 295
 296                         if last_hop {
 297                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 298                                 // it still could overpay for the htlc_minimum_msat.
 299                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 300                         } else {
 301                                 // Propagate updated fees for the use of the channels to one hop back, where they
 302                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 303                                 cur_hop.fee_msat = cur_hop_fees_msat;
 304                         }
 305
 306                         // Fee for the use of the current hop which will be deducted on the previous hop.
 307                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 308                         // this channel is free for us.
 309                         if i != 0 {
 310                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 311                                         cur_hop.hop_use_fee_msat = new_fee;
 312                                         total_fee_paid_msat += new_fee;
 313                                 } else {
 314                                         // It should not be possible because this function is called only to reduce the
 315                                         // value. In that case, compute_fee was already called with the same fees for
 316                                         // larger amount and there was no overflow.
 317                                         unreachable!();
 318                                 }
 319                         }
 320                 }
 321         }
 322 }
 323
 324 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 325         let proportional_fee_millions =
 326                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 327         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 328                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 329
 330                 Some(new_fee)
 331         } else {
 332                 // This function may be (indirectly) called without any verification,
 333                 // with channel_fees provided by a caller. We should handle it gracefully.
 334                 None
 335         }
 336 }
 337
 338 /// Gets a route from us (payer) to the given target node (payee).
 339 ///
 340 /// If the payee provided features in their invoice, they should be provided via payee_features.
 341 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 342 ///
 343 /// Extra routing hops between known nodes and the target will be used if they are included in
 344 /// last_hops.
 345 ///
 346 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 347 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 348 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 349 /// in first_hops will be used.
 350 ///
 351 /// Panics if first_hops contains channels without short_channel_ids
 352 /// (ChannelManager::list_usable_channels will never include such channels).
 353 ///
 354 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 355 /// equal), however the enabled/disabled bit on such channels as well as the
 356 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 357 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 358         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 359         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 360         // uptime/success in using a node in the past.
 361         if *payee == *our_node_id {
 362                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 363         }
 364
 365         if final_value_msat > MAX_VALUE_MSAT {
 366                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 367         }
 368
 369         if final_value_msat == 0 {
 370                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 371         }
 372
 373         for last_hop in last_hops {
 374                 if last_hop.src_node_id == *payee {
 375                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 376                 }
 377         }
 378
 379         // The general routing idea is the following:
 380         // 1. Fill first/last hops communicated by the caller.
 381         // 2. Attempt to construct a path from payer to payee for transferring
 382         //    any ~sufficient (described later) value.
 383         //    If succeed, remember which channels were used and how much liquidity they have available,
 384         //    so that future paths don't rely on the same liquidity.
 385         // 3. Prooceed to the next step if:
 386         //    - we hit the recommended target value;
 387         //    - OR if we could not construct a new path. Any next attempt will fail too.
 388         //    Otherwise, repeat step 2.
 389         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 390         //    (not recommended value). If yes, proceed. If not, fail routing.
 391         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 392         // 6. Of all the found paths, select only those with the lowest total fee.
 393         // 7. The last path in every selected route is likely to be more than we need.
 394         //    Reduce its value-to-transfer and recompute fees.
 395         // 8. Choose the best route by the lowest total fee.
 396
 397         // As for the actual search algorithm,
 398         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 399         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 400         //
 401         // We are not a faithful Dijkstra's implementation because we can change values which impact
 402         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 403         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 404         // the value we are currently attempting to send over a path, we simply reduce the value being
 405         // sent along the path for any hops after that channel. This may imply that later fees (which
 406         // we've already tabulated) are lower because a smaller value is passing through the channels
 407         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 408         // channels which were selected earlier (and which may still be used for other paths without a
 409         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 410         // de-preferenced.
 411         //
 412         // One potentially problematic case for this algorithm would be if there are many
 413         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 414         // graph walking), we may never find a path which is not liquidity-limited and has lower
 415         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 416         // Because we only consider paths with at least 5% of the total value being sent, the damage
 417         // from such a case should be limited, however this could be further reduced in the future by
 418         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 419         // limits for the purposes of fee calculation.
 420         //
 421         // Alternatively, we could store more detailed path information in the heap (targets, below)
 422         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 423         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 424         // and practically (as we would need to store dynamically-allocated path information in heap
 425         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 426         // results of such an algorithm would likely be biased towards lower-value paths.
 427         //
 428         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 429         // outside of our current search value, running a path search more times to gather candidate
 430         // paths at different values. While this may be acceptable, further path searches may increase
 431         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 432         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 433         // the same time, remaining generic across different payment values.
 434         //
 435         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 436         // to use as the A* heuristic beyond just the cost to get one node further than the current
 437         // one.
 438
 439         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 440                 cltv_expiry_delta: 0,
 441                 htlc_minimum_msat: 0,
 442                 htlc_maximum_msat: None,
 443                 fees: RoutingFees {
 444                         base_msat: 0,
 445                         proportional_millionths: 0,
 446                 }
 447         };
 448
 449         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 450         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 451         // work reliably.
 452         let allow_mpp = if let Some(features) = &payee_features {
 453                 features.supports_basic_mpp()
 454         } else if let Some(node) = network.get_nodes().get(&payee) {
 455                 if let Some(node_info) = node.announcement_info.as_ref() {
 456                         node_info.features.supports_basic_mpp()
 457                 } else { false }
 458         } else { false };
 459
 460         // Step (1).
 461         // Prepare the data we'll use for payee-to-payer search by
 462         // inserting first hops suggested by the caller as targets.
 463         // Our search will then attempt to reach them while traversing from the payee node.
 464         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 465                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 466         if let Some(hops) = first_hops {
 467                 for chan in hops {
 468                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 469                         if chan.remote_network_id == *our_node_id {
 470                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 471                         }
 472                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.to_context(), chan.outbound_capacity_msat, chan.counterparty_features.to_context()));
 473                 }
 474                 if first_hop_targets.is_empty() {
 475                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 476                 }
 477         }
 478
 479         let empty_channel_features = ChannelFeatures::empty();
 480
 481         let mut targets = BinaryHeap::new(); //TODO: Do we care about switching to eg Fibbonaci heap?
 482         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 483
 484         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 485         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 486         // htlc_minimum with extra fees while still finding a cheaper path.
 487         let mut hit_minimum_limit;
 488
 489         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 490         // We start with a path_value of the exact amount we want, and if that generates a route we may
 491         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 492         // amount we want in total across paths, selecting the best subset at the end.
 493         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 494         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 495         let mut path_value_msat = final_value_msat;
 496
 497         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 498         // This map allows paths to be aware of the channel use by other paths in the same call.
 499         // This would help to make a better path finding decisions and not "overbook" channels.
 500         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 501         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 502
 503         // Keeping track of how much value we already collected across other paths. Helps to decide:
 504         // - how much a new path should be transferring (upper bound);
 505         // - whether a channel should be disregarded because
 506         //   it's available liquidity is too small comparing to how much more we need to collect;
 507         // - when we want to stop looking for new paths.
 508         let mut already_collected_value_msat = 0;
 509
 510         macro_rules! add_entry {
 511                 // Adds entry which goes from $src_node_id to $dest_node_id
 512                 // over the channel with id $chan_id with fees described in
 513                 // $directional_info.
 514                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 515                 // since that value has to be transferred over this channel.
 516                 ( $chan_id: expr, $src_node_id: expr, $dest_node_id: expr, $directional_info: expr, $capacity_sats: expr, $chan_features: expr, $next_hops_fee_msat: expr,
 517                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 518                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 519                         // practice these cases should be caught earlier:
 520                         // - for regular channels at channel announcement (TODO)
 521                         // - for first and last hops early in get_route
 522                         if $src_node_id != $dest_node_id.clone() {
 523                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 524                                         let mut initial_liquidity_available_msat = None;
 525                                         if let Some(capacity_sats) = $capacity_sats {
 526                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 527                                         }
 528
 529                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 530                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 531                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 532                                                 } else {
 533                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 534                                                 }
 535                                         }
 536
 537                                         match initial_liquidity_available_msat {
 538                                                 Some(available_msat) => available_msat,
 539                                                 // We assume channels with unknown balance have
 540                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 541                                                 None => 250_000 * 1000
 542                                         }
 543                                 });
 544
 545                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 546                                 // It may be misleading because we might later choose to reduce the value transferred
 547                                 // over these channels, and the channel which was insufficient might become sufficient.
 548                                 // Worst case: we drop a good channel here because it can't cover the high following
 549                                 // fees caused by one expensive channel, but then this channel could have been used
 550                                 // if the amount being transferred over this path is lower.
 551                                 // We do this for now, but this is a subject for removal.
 552                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 553
 554                                         // Routing Fragmentation Mitigation heuristic:
 555                                         //
 556                                         // Routing fragmentation across many payment paths increases the overall routing
 557                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 558                                         // Taking too many smaller paths also increases the chance of payment failure.
 559                                         // Thus to avoid this effect, we require from our collected links to provide
 560                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 561                                         //
 562                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 563                                         // This means as we successfully advance in our collection,
 564                                         // the absolute liquidity contribution is lowered,
 565                                         // thus increasing the number of potential channels to be selected.
 566
 567                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 568                                         // or 100% if we're not allowed to do multipath payments.
 569                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 570                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 571                                         } else {
 572                                                 final_value_msat
 573                                         };
 574                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 575                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 576
 577                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 578                                         // Includes paying fees for the use of the following channels.
 579                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 580                                                 Some(result) => result,
 581                                                 // Can't overflow due to how the values were computed right above.
 582                                                 None => unreachable!(),
 583                                         };
 584                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 585                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 586                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 587
 588                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 589                                         // bother considering this channel.
 590                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 591                                         // be only reduced later (not increased), so this channel should just be skipped
 592                                         // as not sufficient.
 593                                         if !over_path_minimum_msat {
 594                                                 hit_minimum_limit = true;
 595                                         } else if contributes_sufficient_value {
 596                                                 // Note that low contribution here (limited by available_liquidity_msat)
 597                                                 // might violate htlc_minimum_msat on the hops which are next along the
 598                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 599                                                 // path fees knowing the final path contribution after constructing it.
 600                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 601                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 602                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 603                                                         _ => u64::max_value()
 604                                                 };
 605                                                 let hm_entry = dist.entry(&$src_node_id);
 606                                                 let old_entry = hm_entry.or_insert_with(|| {
 607                                                         // If there was previously no known way to access
 608                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 609                                                         // a semi-dummy record just to compute the fees to reach the source node.
 610                                                         // This will affect our decision on selecting $chan_id
 611                                                         // as a way to reach the $dest_node_id.
 612                                                         let mut fee_base_msat = u32::max_value();
 613                                                         let mut fee_proportional_millionths = u32::max_value();
 614                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 615                                                                 fee_base_msat = fees.base_msat;
 616                                                                 fee_proportional_millionths = fees.proportional_millionths;
 617                                                         }
 618                                                         PathBuildingHop {
 619                                                                 pubkey: $dest_node_id.clone(),
 620                                                                 short_channel_id: 0,
 621                                                                 channel_features: $chan_features,
 622                                                                 fee_msat: 0,
 623                                                                 cltv_expiry_delta: 0,
 624                                                                 src_lowest_inbound_fees: RoutingFees {
 625                                                                         base_msat: fee_base_msat,
 626                                                                         proportional_millionths: fee_proportional_millionths,
 627                                                                 },
 628                                                                 channel_fees: $directional_info.fees,
 629                                                                 next_hops_fee_msat: u64::max_value(),
 630                                                                 hop_use_fee_msat: u64::max_value(),
 631                                                                 total_fee_msat: u64::max_value(),
 632                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 633                                                                 path_htlc_minimum_msat,
 634                                                                 was_processed: false,
 635                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 636                                                                 value_contribution_msat,
 637                                                         }
 638                                                 });
 639
 640                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 641                                                 let mut should_process = !old_entry.was_processed;
 642                                                 #[cfg(any(test, feature = "fuzztarget"))]
 643                                                 {
 644                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 645                                                         // of already-seen nodes only happens in cases we expect (see below).
 646                                                         if !should_process { should_process = true; }
 647                                                 }
 648
 649                                                 if should_process {
 650                                                         let mut hop_use_fee_msat = 0;
 651                                                         let mut total_fee_msat = $next_hops_fee_msat;
 652
 653                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 654                                                         // will have the same effective-fee
 655                                                         if $src_node_id != *our_node_id {
 656                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 657                                                                         // max_value means we'll always fail
 658                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 659                                                                         None => total_fee_msat = u64::max_value(),
 660                                                                         Some(fee_msat) => {
 661                                                                                 hop_use_fee_msat = fee_msat;
 662                                                                                 total_fee_msat += hop_use_fee_msat;
 663                                                                                 // When calculating the lowest inbound fees to a node, we
 664                                                                                 // calculate fees here not based on the actual value we think
 665                                                                                 // will flow over this channel, but on the minimum value that
 666                                                                                 // we'll accept flowing over it. The minimum accepted value
 667                                                                                 // is a constant through each path collection run, ensuring
 668                                                                                 // consistent basis. Otherwise we may later find a
 669                                                                                 // different path to the source node that is more expensive,
 670                                                                                 // but which we consider to be cheaper because we are capacity
 671                                                                                 // constrained and the relative fee becomes lower.
 672                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 673                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 674                                                                                         Some(Some(v)) => {
 675                                                                                                 total_fee_msat = v;
 676                                                                                         },
 677                                                                                         _ => {
 678                                                                                                 total_fee_msat = u64::max_value();
 679                                                                                         }
 680                                                                                 };
 681                                                                         }
 682                                                                 }
 683                                                         }
 684
 685                                                         let new_graph_node = RouteGraphNode {
 686                                                                 pubkey: $src_node_id,
 687                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 688                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 689                                                                 value_contribution_msat: value_contribution_msat,
 690                                                                 path_htlc_minimum_msat,
 691                                                         };
 692
 693                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 694                                                         // if this way is cheaper than the already known
 695                                                         // (considering the cost to "reach" this channel from the route destination,
 696                                                         // the cost of using this channel,
 697                                                         // and the cost of routing to the source node of this channel).
 698                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 699                                                         // paying it. Consider the following exploit:
 700                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 701                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 702                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 703                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 704                                                         // to this channel.
 705                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 706                                                         // but it may require additional tracking - we don't want to double-count
 707                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 708                                                         // can't use something that may decrease on future hops.
 709                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 710                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 711
 712                                                         if !old_entry.was_processed && new_cost < old_cost {
 713                                                                 targets.push(new_graph_node);
 714                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 715                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 716                                                                 old_entry.total_fee_msat = total_fee_msat;
 717                                                                 old_entry.pubkey = $dest_node_id.clone();
 718                                                                 old_entry.short_channel_id = $chan_id.clone();
 719                                                                 old_entry.channel_features = $chan_features;
 720                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 721                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 722                                                                 old_entry.channel_fees = $directional_info.fees;
 723                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 724                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 725                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 726                                                                 {
 727                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 728                                                                 }
 729                                                         } else if old_entry.was_processed && new_cost < old_cost {
 730                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 731                                                                 {
 732                                                                         // If we're skipping processing a node which was previously
 733                                                                         // processed even though we found another path to it with a
 734                                                                         // cheaper fee, check that it was because the second path we
 735                                                                         // found (which we are processing now) has a lower value
 736                                                                         // contribution due to an HTLC minimum limit.
 737                                                                         //
 738                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 739                                                                         // through channel A, and one through channel B. Channel A and
 740                                                                         // B are both in the to-process heap, with their scores set by
 741                                                                         // a higher htlc_minimum than fee.
 742                                                                         // Channel A is processed first, and the channels onwards from
 743                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 744                                                                         // Channel B off of the heap, note that it has a much more
 745                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 746                                                                         // all of node 1's channels using the new, reduced, amount.
 747                                                                         //
 748                                                                         // This would be bogus - we'd be selecting a higher-fee path
 749                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 750                                                                         // already decided to use.
 751                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 752                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 753                                                                 }
 754                                                         }
 755                                                 }
 756                                         }
 757                                 }
 758                         }
 759                 };
 760         }
 761
 762         let empty_node_features = NodeFeatures::empty();
 763         // Find ways (channels with destination) to reach a given node and store them
 764         // in the corresponding data structures (routing graph etc).
 765         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 766         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 767         // This data can later be helpful to optimize routing (pay lower fees).
 768         macro_rules! add_entries_to_cheapest_to_target_node {
 769                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 770                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 771                                 let was_processed = elem.was_processed;
 772                                 elem.was_processed = true;
 773                                 was_processed
 774                         } else {
 775                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 776                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 777                                 // If we're processing any other node, it is always be the result of a channel from it.
 778                                 assert_eq!($node_id, payee);
 779                                 false
 780                         };
 781
 782                         if !skip_node {
 783                                 if first_hops.is_some() {
 784                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 785                                                 add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 786                                         }
 787                                 }
 788
 789                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 790                                         &node_info.features
 791                                 } else {
 792                                         &empty_node_features
 793                                 };
 794
 795                                 if !features.requires_unknown_bits() {
 796                                         for chan_id in $node.channels.iter() {
 797                                                 let chan = network.get_channels().get(chan_id).unwrap();
 798                                                 if !chan.features.requires_unknown_bits() {
 799                                                         if chan.node_one == *$node_id {
 800                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 801                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 802                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 803                                                                                 if two_to_one.enabled {
 804                                                                                         add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 805                                                                                 }
 806                                                                         }
 807                                                                 }
 808                                                         } else {
 809                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 810                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 811                                                                                 if one_to_two.enabled {
 812                                                                                         add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 813                                                                                 }
 814                                                                         }
 815                                                                 }
 816                                                         }
 817                                                 }
 818                                         }
 819                                 }
 820                         }
 821                 };
 822         }
 823
 824         let mut payment_paths = Vec::<PaymentPath>::new();
 825
 826         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 827         'paths_collection: loop {
 828                 // For every new path, start from scratch, except
 829                 // bookkeeped_channels_liquidity_available_msat, which will improve
 830                 // the further iterations of path finding. Also don't erase first_hop_targets.
 831                 targets.clear();
 832                 dist.clear();
 833                 hit_minimum_limit = false;
 834
 835                 // If first hop is a private channel and the only way to reach the payee, this is the only
 836                 // place where it could be added.
 837                 if first_hops.is_some() {
 838                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 839                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 840                         }
 841                 }
 842
 843                 // Add the payee as a target, so that the payee-to-payer
 844                 // search algorithm knows what to start with.
 845                 match network.get_nodes().get(payee) {
 846                         // The payee is not in our network graph, so nothing to add here.
 847                         // There is still a chance of reaching them via last_hops though,
 848                         // so don't yet fail the payment here.
 849                         // If not, targets.pop() will not even let us enter the loop in step 2.
 850                         None => {},
 851                         Some(node) => {
 852                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 853                         },
 854                 }
 855
 856                 // Step (1).
 857                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 858                 // earlier than general path finding, they will be somewhat prioritized, although currently
 859                 // it matters only if the fees are exactly the same.
 860                 for hop in last_hops.iter() {
 861                         let have_hop_src_in_graph =
 862                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 863                                         // If this hop connects to a node with which we have a direct channel, ignore
 864                                         // the network graph and add both the hop and our direct channel to
 865                                         // the candidate set.
 866                                         //
 867                                         // Currently there are no channel-context features defined, so we are a
 868                                         // bit lazy here. In the future, we should pull them out via our
 869                                         // ChannelManager, but there's no reason to waste the space until we
 870                                         // need them.
 871                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 872                                         true
 873                                 } else {
 874                                         // In any other case, only add the hop if the source is in the regular network
 875                                         // graph:
 876                                         network.get_nodes().get(&hop.src_node_id).is_some()
 877                                 };
 878                         if have_hop_src_in_graph {
 879                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 880                                 // really sucks, cause we're gonna need that eventually.
 881                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 882                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 883                                         None => 0
 884                                 };
 885                                 let directional_info = DummyDirectionalChannelInfo {
 886                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 887                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 888                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 889                                         fees: hop.fees,
 890                                 };
 891                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, &empty_channel_features, 0, path_value_msat, 0);
 892                         }
 893                 }
 894
 895                 // At this point, targets are filled with the data from first and
 896                 // last hops communicated by the caller, and the payment receiver.
 897                 let mut found_new_path = false;
 898
 899                 // Step (2).
 900                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 901                 // - not enough outgoing liquidity:
 902                 //   0 < already_collected_value_msat < final_value_msat
 903                 // - enough outgoing liquidity:
 904                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 905                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 906                 // paths_collection will be stopped because found_new_path==false.
 907                 // This is not necessarily a routing failure.
 908                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 909
 910                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 911                         // traversing the graph and arrange the path out of what we found.
 912                         if pubkey == *our_node_id {
 913                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 914                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 915
 916                                 'path_walk: loop {
 917                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 918                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 919                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 920                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 921                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 922                                                 } else {
 923                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 924                                                 }
 925                                         } else {
 926                                                 // We should be able to fill in features for everything except the last
 927                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 928                                                 // should be able to extend it further as BOLT 11 does have feature
 929                                                 // flags for the last hop node itself).
 930                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
 931                                         }
 932
 933                                         // Means we succesfully traversed from the payer to the payee, now
 934                                         // save this path for the payment route. Also, update the liquidity
 935                                         // remaining on the used hops, so that we take them into account
 936                                         // while looking for more paths.
 937                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
 938                                                 break 'path_walk;
 939                                         }
 940
 941                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
 942                                                 Some(payment_hop) => payment_hop,
 943                                                 // We can't arrive at None because, if we ever add an entry to targets,
 944                                                 // we also fill in the entry in dist (see add_entry!).
 945                                                 None => unreachable!(),
 946                                         };
 947                                         // We "propagate" the fees one hop backward (topologically) here,
 948                                         // so that fees paid for a HTLC forwarding on the current channel are
 949                                         // associated with the previous channel (where they will be subtracted).
 950                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
 951                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
 952                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
 953                                 }
 954                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
 955                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
 956                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
 957
 958                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 959
 960                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 961                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 962                                 // on some channels we already passed (assuming dest->source direction). Here, we
 963                                 // recompute the fees again, so that if that's the case, we match the currently
 964                                 // underpaid htlc_minimum_msat with fees.
 965                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 966
 967                                 // Since a path allows to transfer as much value as
 968                                 // the smallest channel it has ("bottleneck"), we should recompute
 969                                 // the fees so sender HTLC don't overpay fees when traversing
 970                                 // larger channels than the bottleneck. This may happen because
 971                                 // when we were selecting those channels we were not aware how much value
 972                                 // this path will transfer, and the relative fee for them
 973                                 // might have been computed considering a larger value.
 974                                 // Remember that we used these channels so that we don't rely
 975                                 // on the same liquidity in future paths.
 976                                 let mut prevented_redundant_path_selection = false;
 977                                 for (payment_hop, _) in payment_path.hops.iter() {
 978                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
 979                                         let mut spent_on_hop_msat = value_contribution_msat;
 980                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 981                                         spent_on_hop_msat += next_hops_fee_msat;
 982                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
 983                                                 // If this path used all of this channel's available liquidity, we know
 984                                                 // this path will not be selected again in the next loop iteration.
 985                                                 prevented_redundant_path_selection = true;
 986                                         }
 987                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 988                                 }
 989                                 if !prevented_redundant_path_selection {
 990                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 991                                         // we'll probably end up picking the same path again on the next iteration.
 992                                         // Decrease the available liquidity of a hop in the middle of the path.
 993                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 994                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id).unwrap();
 995                                         *victim_liquidity = 0;
 996                                 }
 997
 998                                 // Track the total amount all our collected paths allow to send so that we:
 999                                 // - know when to stop looking for more paths
1000                                 // - know which of the hops are useless considering how much more sats we need
1001                                 //   (contributes_sufficient_value)
1002                                 already_collected_value_msat += value_contribution_msat;
1003
1004                                 payment_paths.push(payment_path);
1005                                 found_new_path = true;
1006                                 break 'path_construction;
1007                         }
1008
1009                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1010                         // the equivalent of the `elem.was_processed` check in
1011                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1012                         if pubkey == *payee { continue 'path_construction; }
1013
1014                         // Otherwise, since the current target node is not us,
1015                         // keep "unrolling" the payment graph from payee to payer by
1016                         // finding a way to reach the current target from the payer side.
1017                         match network.get_nodes().get(&pubkey) {
1018                                 None => {},
1019                                 Some(node) => {
1020                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1021                                 },
1022                         }
1023                 }
1024
1025                 if !allow_mpp {
1026                         // If we don't support MPP, no use trying to gather more value ever.
1027                         break 'paths_collection;
1028                 }
1029
1030                 // Step (3).
1031                 // Stop either when the recommended value is reached or if no new path was found in this
1032                 // iteration.
1033                 // In the latter case, making another path finding attempt won't help,
1034                 // because we deterministically terminated the search due to low liquidity.
1035                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1036                         break 'paths_collection;
1037                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1038                         // Further, if this was our first walk of the graph, and we weren't limited by an
1039                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1040                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1041                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1042                         // still keeping a lower total fee than this path.
1043                         if !hit_minimum_limit {
1044                                 break 'paths_collection;
1045                         }
1046                         path_value_msat = recommended_value_msat;
1047                 }
1048         }
1049
1050         // Step (4).
1051         if payment_paths.len() == 0 {
1052                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1053         }
1054
1055         if already_collected_value_msat < final_value_msat {
1056                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1057         }
1058
1059         // Sort by total fees and take the best paths.
1060         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1061         if payment_paths.len() > 50 {
1062                 payment_paths.truncate(50);
1063         }
1064
1065         // Draw multiple sufficient routes by randomly combining the selected paths.
1066         let mut drawn_routes = Vec::new();
1067         for i in 0..payment_paths.len() {
1068                 let mut cur_route = Vec::<PaymentPath>::new();
1069                 let mut aggregate_route_value_msat = 0;
1070
1071                 // Step (5).
1072                 // TODO: real random shuffle
1073                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1074                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1075
1076                 // Step (6).
1077                 for payment_path in cur_payment_paths {
1078                         cur_route.push(payment_path.clone());
1079                         aggregate_route_value_msat += payment_path.get_value_msat();
1080                         if aggregate_route_value_msat > final_value_msat {
1081                                 // Last path likely overpaid. Substract it from the most expensive
1082                                 // (in terms of proportional fee) path in this route and recompute fees.
1083                                 // This might be not the most economically efficient way, but fewer paths
1084                                 // also makes routing more reliable.
1085                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1086
1087                                 // First, drop some expensive low-value paths entirely if possible.
1088                                 // Sort by value so that we drop many really-low values first, since
1089                                 // fewer paths is better: the payment is less likely to fail.
1090                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1091                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1092                                 cur_route.sort_by_key(|path| path.get_value_msat());
1093                                 // We should make sure that at least 1 path left.
1094                                 let mut paths_left = cur_route.len();
1095                                 cur_route.retain(|path| {
1096                                         if paths_left == 1 {
1097                                                 return true
1098                                         }
1099                                         let mut keep = true;
1100                                         let path_value_msat = path.get_value_msat();
1101                                         if path_value_msat <= overpaid_value_msat {
1102                                                 keep = false;
1103                                                 overpaid_value_msat -= path_value_msat;
1104                                                 paths_left -= 1;
1105                                         }
1106                                         keep
1107                                 });
1108
1109                                 if overpaid_value_msat == 0 {
1110                                         break;
1111                                 }
1112
1113                                 assert!(cur_route.len() > 0);
1114
1115                                 // Step (7).
1116                                 // Now, substract the overpaid value from the most-expensive path.
1117                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1118                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1119                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1120                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1121                                 // We already dropped all the small channels above, meaning all the
1122                                 // remaining channels are larger than remaining overpaid_value_msat.
1123                                 // Thus, this can't be negative.
1124                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1125                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1126                                 break;
1127                         }
1128                 }
1129                 drawn_routes.push(cur_route);
1130         }
1131
1132         // Step (8).
1133         // Select the best route by lowest total fee.
1134         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1135         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1136         for payment_path in drawn_routes.first().unwrap() {
1137                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1138                         RouteHop {
1139                                 pubkey: payment_hop.pubkey,
1140                                 node_features: node_features.clone(),
1141                                 short_channel_id: payment_hop.short_channel_id,
1142                                 channel_features: payment_hop.channel_features.clone(),
1143                                 fee_msat: payment_hop.fee_msat,
1144                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1145                         }
1146                 }).collect());
1147         }
1148
1149         if let Some(features) = &payee_features {
1150                 for path in selected_paths.iter_mut() {
1151                         path.last_mut().unwrap().node_features = features.to_context();
1152                 }
1153         }
1154
1155         let route = Route { paths: selected_paths };
1156         log_trace!(logger, "Got route: {}", log_route!(route));
1157         Ok(route)
1158 }
1159
1160 #[cfg(test)]
1161 mod tests {
1162         use routing::router::{get_route, RouteHint, RoutingFees};
1163         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1164         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1165         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1166            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1167         use ln::channelmanager;
1168         use util::test_utils;
1169         use util::ser::Writeable;
1170
1171         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1172         use bitcoin::hashes::Hash;
1173         use bitcoin::network::constants::Network;
1174         use bitcoin::blockdata::constants::genesis_block;
1175         use bitcoin::blockdata::script::Builder;
1176         use bitcoin::blockdata::opcodes;
1177         use bitcoin::blockdata::transaction::TxOut;
1178
1179         use hex;
1180
1181         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1182         use bitcoin::secp256k1::{Secp256k1, All};
1183
1184         use std::sync::Arc;
1185
1186         // Using the same keys for LN and BTC ids
1187         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1188            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1189                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1190                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1191
1192                 let unsigned_announcement = UnsignedChannelAnnouncement {
1193                         features,
1194                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1195                         short_channel_id,
1196                         node_id_1,
1197                         node_id_2,
1198                         bitcoin_key_1: node_id_1,
1199                         bitcoin_key_2: node_id_2,
1200                         excess_data: Vec::new(),
1201                 };
1202
1203                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1204                 let valid_announcement = ChannelAnnouncement {
1205                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1206                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1207                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1208                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1209                         contents: unsigned_announcement.clone(),
1210                 };
1211                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1212                         Ok(res) => assert!(res),
1213                         _ => panic!()
1214                 };
1215         }
1216
1217         fn update_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate) {
1218                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1219                 let valid_channel_update = ChannelUpdate {
1220                         signature: secp_ctx.sign(&msghash, node_privkey),
1221                         contents: update.clone()
1222                 };
1223
1224                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1225                         Ok(res) => assert!(res),
1226                         Err(_) => panic!()
1227                 };
1228         }
1229
1230         fn add_or_update_node(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey,
1231            features: NodeFeatures, timestamp: u32) {
1232                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1233                 let unsigned_announcement = UnsignedNodeAnnouncement {
1234                         features,
1235                         timestamp,
1236                         node_id,
1237                         rgb: [0; 3],
1238                         alias: [0; 32],
1239                         addresses: Vec::new(),
1240                         excess_address_data: Vec::new(),
1241                         excess_data: Vec::new(),
1242                 };
1243                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1244                 let valid_announcement = NodeAnnouncement {
1245                         signature: secp_ctx.sign(&msghash, node_privkey),
1246                         contents: unsigned_announcement.clone()
1247                 };
1248
1249                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1250                         Ok(_) => (),
1251                         Err(_) => panic!()
1252                 };
1253         }
1254
1255         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1256                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1257                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1258                 }).collect();
1259
1260                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1261
1262                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1263                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1264
1265                 (our_privkey, our_id, privkeys, pubkeys)
1266         }
1267
1268         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1269                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1270                 // test for it later.
1271                 let idx = (id - 1) * 2 + 1;
1272                 if idx > 8*3 {
1273                         vec![1 << (idx - 8*3), 0, 0, 0]
1274                 } else if idx > 8*2 {
1275                         vec![1 << (idx - 8*2), 0, 0]
1276                 } else if idx > 8*1 {
1277                         vec![1 << (idx - 8*1), 0]
1278                 } else {
1279                         vec![1 << idx]
1280                 }
1281         }
1282
1283         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<crate::util::test_utils::TestLogger>>, std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<test_utils::TestLogger>) {
1284                 let secp_ctx = Secp256k1::new();
1285                 let logger = Arc::new(test_utils::TestLogger::new());
1286                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1287                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1288                 // Build network from our_id to node7:
1289                 //
1290                 //        -1(1)2-  node0  -1(3)2-
1291                 //       /                       \
1292                 // our_id -1(12)2- node7 -1(13)2--- node2
1293                 //       \                       /
1294                 //        -1(2)2-  node1  -1(4)2-
1295                 //
1296                 //
1297                 // chan1  1-to-2: disabled
1298                 // chan1  2-to-1: enabled, 0 fee
1299                 //
1300                 // chan2  1-to-2: enabled, ignored fee
1301                 // chan2  2-to-1: enabled, 0 fee
1302                 //
1303                 // chan3  1-to-2: enabled, 0 fee
1304                 // chan3  2-to-1: enabled, 100 msat fee
1305                 //
1306                 // chan4  1-to-2: enabled, 100% fee
1307                 // chan4  2-to-1: enabled, 0 fee
1308                 //
1309                 // chan12 1-to-2: enabled, ignored fee
1310                 // chan12 2-to-1: enabled, 0 fee
1311                 //
1312                 // chan13 1-to-2: enabled, 200% fee
1313                 // chan13 2-to-1: enabled, 0 fee
1314                 //
1315                 //
1316                 //       -1(5)2- node3 -1(8)2--
1317                 //       |         2          |
1318                 //       |       (11)         |
1319                 //      /          1           \
1320                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1321                 //      \                      /
1322                 //       -1(7)2- node5 -1(10)2-
1323                 //
1324                 // chan5  1-to-2: enabled, 100 msat fee
1325                 // chan5  2-to-1: enabled, 0 fee
1326                 //
1327                 // chan6  1-to-2: enabled, 0 fee
1328                 // chan6  2-to-1: enabled, 0 fee
1329                 //
1330                 // chan7  1-to-2: enabled, 100% fee
1331                 // chan7  2-to-1: enabled, 0 fee
1332                 //
1333                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1334                 // chan8  2-to-1: enabled, 0 fee
1335                 //
1336                 // chan9  1-to-2: enabled, 1001 msat fee
1337                 // chan9  2-to-1: enabled, 0 fee
1338                 //
1339                 // chan10 1-to-2: enabled, 0 fee
1340                 // chan10 2-to-1: enabled, 0 fee
1341                 //
1342                 // chan11 1-to-2: enabled, 0 fee
1343                 // chan11 2-to-1: enabled, 0 fee
1344
1345                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1346
1347                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1348                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1349                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1350                         short_channel_id: 1,
1351                         timestamp: 1,
1352                         flags: 1,
1353                         cltv_expiry_delta: 0,
1354                         htlc_minimum_msat: 0,
1355                         htlc_maximum_msat: OptionalField::Absent,
1356                         fee_base_msat: 0,
1357                         fee_proportional_millionths: 0,
1358                         excess_data: Vec::new()
1359                 });
1360
1361                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1362
1363                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1364                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1365                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1366                         short_channel_id: 2,
1367                         timestamp: 1,
1368                         flags: 0,
1369                         cltv_expiry_delta: u16::max_value(),
1370                         htlc_minimum_msat: 0,
1371                         htlc_maximum_msat: OptionalField::Absent,
1372                         fee_base_msat: u32::max_value(),
1373                         fee_proportional_millionths: u32::max_value(),
1374                         excess_data: Vec::new()
1375                 });
1376                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1377                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1378                         short_channel_id: 2,
1379                         timestamp: 1,
1380                         flags: 1,
1381                         cltv_expiry_delta: 0,
1382                         htlc_minimum_msat: 0,
1383                         htlc_maximum_msat: OptionalField::Absent,
1384                         fee_base_msat: 0,
1385                         fee_proportional_millionths: 0,
1386                         excess_data: Vec::new()
1387                 });
1388
1389                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1390
1391                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1392                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1393                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1394                         short_channel_id: 12,
1395                         timestamp: 1,
1396                         flags: 0,
1397                         cltv_expiry_delta: u16::max_value(),
1398                         htlc_minimum_msat: 0,
1399                         htlc_maximum_msat: OptionalField::Absent,
1400                         fee_base_msat: u32::max_value(),
1401                         fee_proportional_millionths: u32::max_value(),
1402                         excess_data: Vec::new()
1403                 });
1404                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1405                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1406                         short_channel_id: 12,
1407                         timestamp: 1,
1408                         flags: 1,
1409                         cltv_expiry_delta: 0,
1410                         htlc_minimum_msat: 0,
1411                         htlc_maximum_msat: OptionalField::Absent,
1412                         fee_base_msat: 0,
1413                         fee_proportional_millionths: 0,
1414                         excess_data: Vec::new()
1415                 });
1416
1417                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1418
1419                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1420                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1421                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1422                         short_channel_id: 3,
1423                         timestamp: 1,
1424                         flags: 0,
1425                         cltv_expiry_delta: (3 << 8) | 1,
1426                         htlc_minimum_msat: 0,
1427                         htlc_maximum_msat: OptionalField::Absent,
1428                         fee_base_msat: 0,
1429                         fee_proportional_millionths: 0,
1430                         excess_data: Vec::new()
1431                 });
1432                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1433                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1434                         short_channel_id: 3,
1435                         timestamp: 1,
1436                         flags: 1,
1437                         cltv_expiry_delta: (3 << 8) | 2,
1438                         htlc_minimum_msat: 0,
1439                         htlc_maximum_msat: OptionalField::Absent,
1440                         fee_base_msat: 100,
1441                         fee_proportional_millionths: 0,
1442                         excess_data: Vec::new()
1443                 });
1444
1445                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1446                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1447                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1448                         short_channel_id: 4,
1449                         timestamp: 1,
1450                         flags: 0,
1451                         cltv_expiry_delta: (4 << 8) | 1,
1452                         htlc_minimum_msat: 0,
1453                         htlc_maximum_msat: OptionalField::Absent,
1454                         fee_base_msat: 0,
1455                         fee_proportional_millionths: 1000000,
1456                         excess_data: Vec::new()
1457                 });
1458                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1459                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1460                         short_channel_id: 4,
1461                         timestamp: 1,
1462                         flags: 1,
1463                         cltv_expiry_delta: (4 << 8) | 2,
1464                         htlc_minimum_msat: 0,
1465                         htlc_maximum_msat: OptionalField::Absent,
1466                         fee_base_msat: 0,
1467                         fee_proportional_millionths: 0,
1468                         excess_data: Vec::new()
1469                 });
1470
1471                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1472                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1473                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1474                         short_channel_id: 13,
1475                         timestamp: 1,
1476                         flags: 0,
1477                         cltv_expiry_delta: (13 << 8) | 1,
1478                         htlc_minimum_msat: 0,
1479                         htlc_maximum_msat: OptionalField::Absent,
1480                         fee_base_msat: 0,
1481                         fee_proportional_millionths: 2000000,
1482                         excess_data: Vec::new()
1483                 });
1484                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1485                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1486                         short_channel_id: 13,
1487                         timestamp: 1,
1488                         flags: 1,
1489                         cltv_expiry_delta: (13 << 8) | 2,
1490                         htlc_minimum_msat: 0,
1491                         htlc_maximum_msat: OptionalField::Absent,
1492                         fee_base_msat: 0,
1493                         fee_proportional_millionths: 0,
1494                         excess_data: Vec::new()
1495                 });
1496
1497                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1498
1499                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1500                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1501                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1502                         short_channel_id: 6,
1503                         timestamp: 1,
1504                         flags: 0,
1505                         cltv_expiry_delta: (6 << 8) | 1,
1506                         htlc_minimum_msat: 0,
1507                         htlc_maximum_msat: OptionalField::Absent,
1508                         fee_base_msat: 0,
1509                         fee_proportional_millionths: 0,
1510                         excess_data: Vec::new()
1511                 });
1512                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1513                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1514                         short_channel_id: 6,
1515                         timestamp: 1,
1516                         flags: 1,
1517                         cltv_expiry_delta: (6 << 8) | 2,
1518                         htlc_minimum_msat: 0,
1519                         htlc_maximum_msat: OptionalField::Absent,
1520                         fee_base_msat: 0,
1521                         fee_proportional_millionths: 0,
1522                         excess_data: Vec::new(),
1523                 });
1524
1525                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1526                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1527                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1528                         short_channel_id: 11,
1529                         timestamp: 1,
1530                         flags: 0,
1531                         cltv_expiry_delta: (11 << 8) | 1,
1532                         htlc_minimum_msat: 0,
1533                         htlc_maximum_msat: OptionalField::Absent,
1534                         fee_base_msat: 0,
1535                         fee_proportional_millionths: 0,
1536                         excess_data: Vec::new()
1537                 });
1538                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1539                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1540                         short_channel_id: 11,
1541                         timestamp: 1,
1542                         flags: 1,
1543                         cltv_expiry_delta: (11 << 8) | 2,
1544                         htlc_minimum_msat: 0,
1545                         htlc_maximum_msat: OptionalField::Absent,
1546                         fee_base_msat: 0,
1547                         fee_proportional_millionths: 0,
1548                         excess_data: Vec::new()
1549                 });
1550
1551                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1552
1553                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1554
1555                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1556                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1557                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1558                         short_channel_id: 7,
1559                         timestamp: 1,
1560                         flags: 0,
1561                         cltv_expiry_delta: (7 << 8) | 1,
1562                         htlc_minimum_msat: 0,
1563                         htlc_maximum_msat: OptionalField::Absent,
1564                         fee_base_msat: 0,
1565                         fee_proportional_millionths: 1000000,
1566                         excess_data: Vec::new()
1567                 });
1568                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1569                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1570                         short_channel_id: 7,
1571                         timestamp: 1,
1572                         flags: 1,
1573                         cltv_expiry_delta: (7 << 8) | 2,
1574                         htlc_minimum_msat: 0,
1575                         htlc_maximum_msat: OptionalField::Absent,
1576                         fee_base_msat: 0,
1577                         fee_proportional_millionths: 0,
1578                         excess_data: Vec::new()
1579                 });
1580
1581                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1582
1583                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1584         }
1585
1586         #[test]
1587         fn simple_route_test() {
1588                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1589                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1590
1591                 // Simple route to 2 via 1
1592
1593                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1594                         assert_eq!(err, "Cannot send a payment of 0 msat");
1595                 } else { panic!(); }
1596
1597                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1598                 assert_eq!(route.paths[0].len(), 2);
1599
1600                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1601                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1602                 assert_eq!(route.paths[0][0].fee_msat, 100);
1603                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1604                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1605                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1606
1607                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1608                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1609                 assert_eq!(route.paths[0][1].fee_msat, 100);
1610                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1611                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1612                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1613         }
1614
1615         #[test]
1616         fn invalid_first_hop_test() {
1617                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1618                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1619
1620                 // Simple route to 2 via 1
1621
1622                 let our_chans = vec![channelmanager::ChannelDetails {
1623                         channel_id: [0; 32],
1624                         short_channel_id: Some(2),
1625                         remote_network_id: our_id,
1626                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1627                         channel_value_satoshis: 100000,
1628                         user_id: 0,
1629                         outbound_capacity_msat: 100000,
1630                         inbound_capacity_msat: 100000,
1631                         is_live: true,
1632                         counterparty_forwarding_info: None,
1633                 }];
1634
1635                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1636                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1637                 } else { panic!(); }
1638
1639                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1640                 assert_eq!(route.paths[0].len(), 2);
1641         }
1642
1643         #[test]
1644         fn htlc_minimum_test() {
1645                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1646                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1647
1648                 // Simple route to 2 via 1
1649
1650                 // Disable other paths
1651                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1652                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1653                         short_channel_id: 12,
1654                         timestamp: 2,
1655                         flags: 2, // to disable
1656                         cltv_expiry_delta: 0,
1657                         htlc_minimum_msat: 0,
1658                         htlc_maximum_msat: OptionalField::Absent,
1659                         fee_base_msat: 0,
1660                         fee_proportional_millionths: 0,
1661                         excess_data: Vec::new()
1662                 });
1663                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1664                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1665                         short_channel_id: 3,
1666                         timestamp: 2,
1667                         flags: 2, // to disable
1668                         cltv_expiry_delta: 0,
1669                         htlc_minimum_msat: 0,
1670                         htlc_maximum_msat: OptionalField::Absent,
1671                         fee_base_msat: 0,
1672                         fee_proportional_millionths: 0,
1673                         excess_data: Vec::new()
1674                 });
1675                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1676                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1677                         short_channel_id: 13,
1678                         timestamp: 2,
1679                         flags: 2, // to disable
1680                         cltv_expiry_delta: 0,
1681                         htlc_minimum_msat: 0,
1682                         htlc_maximum_msat: OptionalField::Absent,
1683                         fee_base_msat: 0,
1684                         fee_proportional_millionths: 0,
1685                         excess_data: Vec::new()
1686                 });
1687                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1688                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1689                         short_channel_id: 6,
1690                         timestamp: 2,
1691                         flags: 2, // to disable
1692                         cltv_expiry_delta: 0,
1693                         htlc_minimum_msat: 0,
1694                         htlc_maximum_msat: OptionalField::Absent,
1695                         fee_base_msat: 0,
1696                         fee_proportional_millionths: 0,
1697                         excess_data: Vec::new()
1698                 });
1699                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1700                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1701                         short_channel_id: 7,
1702                         timestamp: 2,
1703                         flags: 2, // to disable
1704                         cltv_expiry_delta: 0,
1705                         htlc_minimum_msat: 0,
1706                         htlc_maximum_msat: OptionalField::Absent,
1707                         fee_base_msat: 0,
1708                         fee_proportional_millionths: 0,
1709                         excess_data: Vec::new()
1710                 });
1711
1712                 // Check against amount_to_transfer_over_msat.
1713                 // Set minimal HTLC of 200_000_000 msat.
1714                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1715                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1716                         short_channel_id: 2,
1717                         timestamp: 3,
1718                         flags: 0,
1719                         cltv_expiry_delta: 0,
1720                         htlc_minimum_msat: 200_000_000,
1721                         htlc_maximum_msat: OptionalField::Absent,
1722                         fee_base_msat: 0,
1723                         fee_proportional_millionths: 0,
1724                         excess_data: Vec::new()
1725                 });
1726
1727                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1728                 // be used.
1729                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1730                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1731                         short_channel_id: 4,
1732                         timestamp: 3,
1733                         flags: 0,
1734                         cltv_expiry_delta: 0,
1735                         htlc_minimum_msat: 0,
1736                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1737                         fee_base_msat: 0,
1738                         fee_proportional_millionths: 0,
1739                         excess_data: Vec::new()
1740                 });
1741
1742                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1743                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1744                         assert_eq!(err, "Failed to find a path to the given destination");
1745                 } else { panic!(); }
1746
1747                 // Lift the restriction on the first hop.
1748                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1749                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1750                         short_channel_id: 2,
1751                         timestamp: 4,
1752                         flags: 0,
1753                         cltv_expiry_delta: 0,
1754                         htlc_minimum_msat: 0,
1755                         htlc_maximum_msat: OptionalField::Absent,
1756                         fee_base_msat: 0,
1757                         fee_proportional_millionths: 0,
1758                         excess_data: Vec::new()
1759                 });
1760
1761                 // A payment above the minimum should pass
1762                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1763                 assert_eq!(route.paths[0].len(), 2);
1764         }
1765
1766         #[test]
1767         fn htlc_minimum_overpay_test() {
1768                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1769                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1770
1771                 // A route to node#2 via two paths.
1772                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1773                 // Thus, they can't send 60 without overpaying.
1774                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1775                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1776                         short_channel_id: 2,
1777                         timestamp: 2,
1778                         flags: 0,
1779                         cltv_expiry_delta: 0,
1780                         htlc_minimum_msat: 35_000,
1781                         htlc_maximum_msat: OptionalField::Present(40_000),
1782                         fee_base_msat: 0,
1783                         fee_proportional_millionths: 0,
1784                         excess_data: Vec::new()
1785                 });
1786                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1787                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1788                         short_channel_id: 12,
1789                         timestamp: 3,
1790                         flags: 0,
1791                         cltv_expiry_delta: 0,
1792                         htlc_minimum_msat: 35_000,
1793                         htlc_maximum_msat: OptionalField::Present(40_000),
1794                         fee_base_msat: 0,
1795                         fee_proportional_millionths: 0,
1796                         excess_data: Vec::new()
1797                 });
1798
1799                 // Make 0 fee.
1800                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1801                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1802                         short_channel_id: 13,
1803                         timestamp: 2,
1804                         flags: 0,
1805                         cltv_expiry_delta: 0,
1806                         htlc_minimum_msat: 0,
1807                         htlc_maximum_msat: OptionalField::Absent,
1808                         fee_base_msat: 0,
1809                         fee_proportional_millionths: 0,
1810                         excess_data: Vec::new()
1811                 });
1812                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1813                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1814                         short_channel_id: 4,
1815                         timestamp: 2,
1816                         flags: 0,
1817                         cltv_expiry_delta: 0,
1818                         htlc_minimum_msat: 0,
1819                         htlc_maximum_msat: OptionalField::Absent,
1820                         fee_base_msat: 0,
1821                         fee_proportional_millionths: 0,
1822                         excess_data: Vec::new()
1823                 });
1824
1825                 // Disable other paths
1826                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1827                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1828                         short_channel_id: 1,
1829                         timestamp: 3,
1830                         flags: 2, // to disable
1831                         cltv_expiry_delta: 0,
1832                         htlc_minimum_msat: 0,
1833                         htlc_maximum_msat: OptionalField::Absent,
1834                         fee_base_msat: 0,
1835                         fee_proportional_millionths: 0,
1836                         excess_data: Vec::new()
1837                 });
1838
1839                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1840                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1841                 // Overpay fees to hit htlc_minimum_msat.
1842                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1843                 // TODO: this could be better balanced to overpay 10k and not 15k.
1844                 assert_eq!(overpaid_fees, 15_000);
1845
1846                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1847                 // while taking even more fee to match htlc_minimum_msat.
1848                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1849                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1850                         short_channel_id: 12,
1851                         timestamp: 4,
1852                         flags: 0,
1853                         cltv_expiry_delta: 0,
1854                         htlc_minimum_msat: 65_000,
1855                         htlc_maximum_msat: OptionalField::Present(80_000),
1856                         fee_base_msat: 0,
1857                         fee_proportional_millionths: 0,
1858                         excess_data: Vec::new()
1859                 });
1860                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1861                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1862                         short_channel_id: 2,
1863                         timestamp: 3,
1864                         flags: 0,
1865                         cltv_expiry_delta: 0,
1866                         htlc_minimum_msat: 0,
1867                         htlc_maximum_msat: OptionalField::Absent,
1868                         fee_base_msat: 0,
1869                         fee_proportional_millionths: 0,
1870                         excess_data: Vec::new()
1871                 });
1872                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1873                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1874                         short_channel_id: 4,
1875                         timestamp: 4,
1876                         flags: 0,
1877                         cltv_expiry_delta: 0,
1878                         htlc_minimum_msat: 0,
1879                         htlc_maximum_msat: OptionalField::Absent,
1880                         fee_base_msat: 0,
1881                         fee_proportional_millionths: 100_000,
1882                         excess_data: Vec::new()
1883                 });
1884
1885                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1886                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1887                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1888                 assert_eq!(route.paths.len(), 1);
1889                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1890                 let fees = route.paths[0][0].fee_msat;
1891                 assert_eq!(fees, 5_000);
1892
1893                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1894                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1895                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1896                 // the other channel.
1897                 assert_eq!(route.paths.len(), 1);
1898                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1899                 let fees = route.paths[0][0].fee_msat;
1900                 assert_eq!(fees, 5_000);
1901         }
1902
1903         #[test]
1904         fn disable_channels_test() {
1905                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1906                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1907
1908                 // // Disable channels 4 and 12 by flags=2
1909                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1910                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1911                         short_channel_id: 4,
1912                         timestamp: 2,
1913                         flags: 2, // to disable
1914                         cltv_expiry_delta: 0,
1915                         htlc_minimum_msat: 0,
1916                         htlc_maximum_msat: OptionalField::Absent,
1917                         fee_base_msat: 0,
1918                         fee_proportional_millionths: 0,
1919                         excess_data: Vec::new()
1920                 });
1921                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1922                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1923                         short_channel_id: 12,
1924                         timestamp: 2,
1925                         flags: 2, // to disable
1926                         cltv_expiry_delta: 0,
1927                         htlc_minimum_msat: 0,
1928                         htlc_maximum_msat: OptionalField::Absent,
1929                         fee_base_msat: 0,
1930                         fee_proportional_millionths: 0,
1931                         excess_data: Vec::new()
1932                 });
1933
1934                 // If all the channels require some features we don't understand, route should fail
1935                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1936                         assert_eq!(err, "Failed to find a path to the given destination");
1937                 } else { panic!(); }
1938
1939                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1940                 let our_chans = vec![channelmanager::ChannelDetails {
1941                         channel_id: [0; 32],
1942                         short_channel_id: Some(42),
1943                         remote_network_id: nodes[7].clone(),
1944                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1945                         channel_value_satoshis: 0,
1946                         user_id: 0,
1947                         outbound_capacity_msat: 250_000_000,
1948                         inbound_capacity_msat: 0,
1949                         is_live: true,
1950                         counterparty_forwarding_info: None,
1951                 }];
1952                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1953                 assert_eq!(route.paths[0].len(), 2);
1954
1955                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1956                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1957                 assert_eq!(route.paths[0][0].fee_msat, 200);
1958                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1959                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1960                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1961
1962                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1963                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1964                 assert_eq!(route.paths[0][1].fee_msat, 100);
1965                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1966                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1967                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1968         }
1969
1970         #[test]
1971         fn disable_node_test() {
1972                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1973                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1974
1975                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1976                 let mut unknown_features = NodeFeatures::known();
1977                 unknown_features.set_required_unknown_bits();
1978                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1979                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1980                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1981
1982                 // If all nodes require some features we don't understand, route should fail
1983                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1984                         assert_eq!(err, "Failed to find a path to the given destination");
1985                 } else { panic!(); }
1986
1987                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1988                 let our_chans = vec![channelmanager::ChannelDetails {
1989                         channel_id: [0; 32],
1990                         short_channel_id: Some(42),
1991                         remote_network_id: nodes[7].clone(),
1992                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1993                         channel_value_satoshis: 0,
1994                         user_id: 0,
1995                         outbound_capacity_msat: 250_000_000,
1996                         inbound_capacity_msat: 0,
1997                         is_live: true,
1998                         counterparty_forwarding_info: None,
1999                 }];
2000                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2001                 assert_eq!(route.paths[0].len(), 2);
2002
2003                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2004                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2005                 assert_eq!(route.paths[0][0].fee_msat, 200);
2006                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2007                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2008                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2009
2010                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2011                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2012                 assert_eq!(route.paths[0][1].fee_msat, 100);
2013                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2014                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2015                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2016
2017                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2018                 // naively) assume that the user checked the feature bits on the invoice, which override
2019                 // the node_announcement.
2020         }
2021
2022         #[test]
2023         fn our_chans_test() {
2024                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2025                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2026
2027                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2028                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2029                 assert_eq!(route.paths[0].len(), 3);
2030
2031                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2032                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2033                 assert_eq!(route.paths[0][0].fee_msat, 200);
2034                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2035                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2036                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2037
2038                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2039                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2040                 assert_eq!(route.paths[0][1].fee_msat, 100);
2041                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2042                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2043                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2044
2045                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2046                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2047                 assert_eq!(route.paths[0][2].fee_msat, 100);
2048                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2049                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2050                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2051
2052                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2053                 let our_chans = vec![channelmanager::ChannelDetails {
2054                         channel_id: [0; 32],
2055                         short_channel_id: Some(42),
2056                         remote_network_id: nodes[7].clone(),
2057                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2058                         channel_value_satoshis: 0,
2059                         user_id: 0,
2060                         outbound_capacity_msat: 250_000_000,
2061                         inbound_capacity_msat: 0,
2062                         is_live: true,
2063                         counterparty_forwarding_info: None,
2064                 }];
2065                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2066                 assert_eq!(route.paths[0].len(), 2);
2067
2068                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2069                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2070                 assert_eq!(route.paths[0][0].fee_msat, 200);
2071                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2072                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2073                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2074
2075                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2076                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2077                 assert_eq!(route.paths[0][1].fee_msat, 100);
2078                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2079                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2080                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2081         }
2082
2083         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2084                 let zero_fees = RoutingFees {
2085                         base_msat: 0,
2086                         proportional_millionths: 0,
2087                 };
2088                 vec!(RouteHint {
2089                         src_node_id: nodes[3].clone(),
2090                         short_channel_id: 8,
2091                         fees: zero_fees,
2092                         cltv_expiry_delta: (8 << 8) | 1,
2093                         htlc_minimum_msat: None,
2094                         htlc_maximum_msat: None,
2095                 }, RouteHint {
2096                         src_node_id: nodes[4].clone(),
2097                         short_channel_id: 9,
2098                         fees: RoutingFees {
2099                                 base_msat: 1001,
2100                                 proportional_millionths: 0,
2101                         },
2102                         cltv_expiry_delta: (9 << 8) | 1,
2103                         htlc_minimum_msat: None,
2104                         htlc_maximum_msat: None,
2105                 }, RouteHint {
2106                         src_node_id: nodes[5].clone(),
2107                         short_channel_id: 10,
2108                         fees: zero_fees,
2109                         cltv_expiry_delta: (10 << 8) | 1,
2110                         htlc_minimum_msat: None,
2111                         htlc_maximum_msat: None,
2112                 })
2113         }
2114
2115         #[test]
2116         fn last_hops_test() {
2117                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2118                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2119
2120                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2121
2122                 // First check that lst hop can't have its source as the payee.
2123                 let invalid_last_hop = RouteHint {
2124                         src_node_id: nodes[6],
2125                         short_channel_id: 8,
2126                         fees: RoutingFees {
2127                                 base_msat: 1000,
2128                                 proportional_millionths: 0,
2129                         },
2130                         cltv_expiry_delta: (8 << 8) | 1,
2131                         htlc_minimum_msat: None,
2132                         htlc_maximum_msat: None,
2133                 };
2134
2135                 let mut invalid_last_hops = last_hops(&nodes);
2136                 invalid_last_hops.push(invalid_last_hop);
2137                 {
2138                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2139                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2140                         } else { panic!(); }
2141                 }
2142
2143                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2144                 assert_eq!(route.paths[0].len(), 5);
2145
2146                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2147                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2148                 assert_eq!(route.paths[0][0].fee_msat, 100);
2149                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2150                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2151                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2152
2153                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2154                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2155                 assert_eq!(route.paths[0][1].fee_msat, 0);
2156                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2157                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2158                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2159
2160                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2161                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2162                 assert_eq!(route.paths[0][2].fee_msat, 0);
2163                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2164                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2165                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2166
2167                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2168                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2169                 assert_eq!(route.paths[0][3].fee_msat, 0);
2170                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2171                 // If we have a peer in the node map, we'll use their features here since we don't have
2172                 // a way of figuring out their features from the invoice:
2173                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2174                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2175
2176                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2177                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2178                 assert_eq!(route.paths[0][4].fee_msat, 100);
2179                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2180                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2181                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2182         }
2183
2184         #[test]
2185         fn our_chans_last_hop_connect_test() {
2186                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2187                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2188
2189                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2190                 let our_chans = vec![channelmanager::ChannelDetails {
2191                         channel_id: [0; 32],
2192                         short_channel_id: Some(42),
2193                         remote_network_id: nodes[3].clone(),
2194                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2195                         channel_value_satoshis: 0,
2196                         user_id: 0,
2197                         outbound_capacity_msat: 250_000_000,
2198                         inbound_capacity_msat: 0,
2199                         is_live: true,
2200                         counterparty_forwarding_info: None,
2201                 }];
2202                 let mut last_hops = last_hops(&nodes);
2203                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2204                 assert_eq!(route.paths[0].len(), 2);
2205
2206                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2207                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2208                 assert_eq!(route.paths[0][0].fee_msat, 0);
2209                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2210                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2211                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2212
2213                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2214                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2215                 assert_eq!(route.paths[0][1].fee_msat, 100);
2216                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2217                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2218                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2219
2220                 last_hops[0].fees.base_msat = 1000;
2221
2222                 // Revert to via 6 as the fee on 8 goes up
2223                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2224                 assert_eq!(route.paths[0].len(), 4);
2225
2226                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2227                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2228                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2229                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2230                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2231                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2232
2233                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2234                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2235                 assert_eq!(route.paths[0][1].fee_msat, 100);
2236                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2237                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2238                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2239
2240                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2241                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2242                 assert_eq!(route.paths[0][2].fee_msat, 0);
2243                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2244                 // If we have a peer in the node map, we'll use their features here since we don't have
2245                 // a way of figuring out their features from the invoice:
2246                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2247                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2248
2249                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2250                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2251                 assert_eq!(route.paths[0][3].fee_msat, 100);
2252                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2253                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2254                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2255
2256                 // ...but still use 8 for larger payments as 6 has a variable feerate
2257                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2258                 assert_eq!(route.paths[0].len(), 5);
2259
2260                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2261                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2262                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2263                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2264                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2265                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2266
2267                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2268                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2269                 assert_eq!(route.paths[0][1].fee_msat, 0);
2270                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2271                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2272                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2273
2274                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2275                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2276                 assert_eq!(route.paths[0][2].fee_msat, 0);
2277                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2278                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2279                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2280
2281                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2282                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2283                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2284                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2285                 // If we have a peer in the node map, we'll use their features here since we don't have
2286                 // a way of figuring out their features from the invoice:
2287                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2288                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2289
2290                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2291                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2292                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2293                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2294                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2295                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2296         }
2297
2298         #[test]
2299         fn unannounced_path_test() {
2300                 // We should be able to send a payment to a destination without any help of a routing graph
2301                 // if we have a channel with a common counterparty that appears in the first and last hop
2302                 // hints.
2303                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2304                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2305                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2306
2307                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2308                 let last_hops = vec![RouteHint {
2309                         src_node_id: middle_node_id,
2310                         short_channel_id: 8,
2311                         fees: RoutingFees {
2312                                 base_msat: 1000,
2313                                 proportional_millionths: 0,
2314                         },
2315                         cltv_expiry_delta: (8 << 8) | 1,
2316                         htlc_minimum_msat: None,
2317                         htlc_maximum_msat: None,
2318                 }];
2319                 let our_chans = vec![channelmanager::ChannelDetails {
2320                         channel_id: [0; 32],
2321                         short_channel_id: Some(42),
2322                         remote_network_id: middle_node_id,
2323                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2324                         channel_value_satoshis: 100000,
2325                         user_id: 0,
2326                         outbound_capacity_msat: 100000,
2327                         inbound_capacity_msat: 100000,
2328                         is_live: true,
2329                         counterparty_forwarding_info: None,
2330                 }];
2331                 let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
2332
2333                 assert_eq!(route.paths[0].len(), 2);
2334
2335                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2336                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2337                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2338                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2339                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2340                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2341
2342                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2343                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2344                 assert_eq!(route.paths[0][1].fee_msat, 100);
2345                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2346                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2347                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2348         }
2349
2350         #[test]
2351         fn available_amount_while_routing_test() {
2352                 // Tests whether we choose the correct available channel amount while routing.
2353
2354                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2355                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2356
2357                 // We will use a simple single-path route from
2358                 // our node to node2 via node0: channels {1, 3}.
2359
2360                 // First disable all other paths.
2361                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2362                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2363                         short_channel_id: 2,
2364                         timestamp: 2,
2365                         flags: 2,
2366                         cltv_expiry_delta: 0,
2367                         htlc_minimum_msat: 0,
2368                         htlc_maximum_msat: OptionalField::Present(100_000),
2369                         fee_base_msat: 0,
2370                         fee_proportional_millionths: 0,
2371                         excess_data: Vec::new()
2372                 });
2373                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2374                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2375                         short_channel_id: 12,
2376                         timestamp: 2,
2377                         flags: 2,
2378                         cltv_expiry_delta: 0,
2379                         htlc_minimum_msat: 0,
2380                         htlc_maximum_msat: OptionalField::Present(100_000),
2381                         fee_base_msat: 0,
2382                         fee_proportional_millionths: 0,
2383                         excess_data: Vec::new()
2384                 });
2385
2386                 // Make the first channel (#1) very permissive,
2387                 // and we will be testing all limits on the second channel.
2388                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2389                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2390                         short_channel_id: 1,
2391                         timestamp: 2,
2392                         flags: 0,
2393                         cltv_expiry_delta: 0,
2394                         htlc_minimum_msat: 0,
2395                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2396                         fee_base_msat: 0,
2397                         fee_proportional_millionths: 0,
2398                         excess_data: Vec::new()
2399                 });
2400
2401                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2402                 // In this case, it should be set to 250_000 sats.
2403                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2404                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2405                         short_channel_id: 3,
2406                         timestamp: 2,
2407                         flags: 0,
2408                         cltv_expiry_delta: 0,
2409                         htlc_minimum_msat: 0,
2410                         htlc_maximum_msat: OptionalField::Absent,
2411                         fee_base_msat: 0,
2412                         fee_proportional_millionths: 0,
2413                         excess_data: Vec::new()
2414                 });
2415
2416                 {
2417                         // Attempt to route more than available results in a failure.
2418                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2419                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2420                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2421                         } else { panic!(); }
2422                 }
2423
2424                 {
2425                         // Now, attempt to route an exact amount we have should be fine.
2426                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2427                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2428                         assert_eq!(route.paths.len(), 1);
2429                         let path = route.paths.last().unwrap();
2430                         assert_eq!(path.len(), 2);
2431                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2432                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2433                 }
2434
2435                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2436                 // Disable channel #1 and use another first hop.
2437                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2438                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2439                         short_channel_id: 1,
2440                         timestamp: 3,
2441                         flags: 2,
2442                         cltv_expiry_delta: 0,
2443                         htlc_minimum_msat: 0,
2444                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2445                         fee_base_msat: 0,
2446                         fee_proportional_millionths: 0,
2447                         excess_data: Vec::new()
2448                 });
2449
2450                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2451                 let our_chans = vec![channelmanager::ChannelDetails {
2452                         channel_id: [0; 32],
2453                         short_channel_id: Some(42),
2454                         remote_network_id: nodes[0].clone(),
2455                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2456                         channel_value_satoshis: 0,
2457                         user_id: 0,
2458                         outbound_capacity_msat: 200_000_000,
2459                         inbound_capacity_msat: 0,
2460                         is_live: true,
2461                         counterparty_forwarding_info: None,
2462                 }];
2463
2464                 {
2465                         // Attempt to route more than available results in a failure.
2466                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2467                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2468                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2469                         } else { panic!(); }
2470                 }
2471
2472                 {
2473                         // Now, attempt to route an exact amount we have should be fine.
2474                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2475                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2476                         assert_eq!(route.paths.len(), 1);
2477                         let path = route.paths.last().unwrap();
2478                         assert_eq!(path.len(), 2);
2479                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2480                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2481                 }
2482
2483                 // Enable channel #1 back.
2484                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2485                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2486                         short_channel_id: 1,
2487                         timestamp: 4,
2488                         flags: 0,
2489                         cltv_expiry_delta: 0,
2490                         htlc_minimum_msat: 0,
2491                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2492                         fee_base_msat: 0,
2493                         fee_proportional_millionths: 0,
2494                         excess_data: Vec::new()
2495                 });
2496
2497
2498                 // Now let's see if routing works if we know only htlc_maximum_msat.
2499                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2500                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2501                         short_channel_id: 3,
2502                         timestamp: 3,
2503                         flags: 0,
2504                         cltv_expiry_delta: 0,
2505                         htlc_minimum_msat: 0,
2506                         htlc_maximum_msat: OptionalField::Present(15_000),
2507                         fee_base_msat: 0,
2508                         fee_proportional_millionths: 0,
2509                         excess_data: Vec::new()
2510                 });
2511
2512                 {
2513                         // Attempt to route more than available results in a failure.
2514                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2515                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2516                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2517                         } else { panic!(); }
2518                 }
2519
2520                 {
2521                         // Now, attempt to route an exact amount we have should be fine.
2522                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2523                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2524                         assert_eq!(route.paths.len(), 1);
2525                         let path = route.paths.last().unwrap();
2526                         assert_eq!(path.len(), 2);
2527                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2528                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2529                 }
2530
2531                 // Now let's see if routing works if we know only capacity from the UTXO.
2532
2533                 // We can't change UTXO capacity on the fly, so we'll disable
2534                 // the existing channel and add another one with the capacity we need.
2535                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2536                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2537                         short_channel_id: 3,
2538                         timestamp: 4,
2539                         flags: 2,
2540                         cltv_expiry_delta: 0,
2541                         htlc_minimum_msat: 0,
2542                         htlc_maximum_msat: OptionalField::Absent,
2543                         fee_base_msat: 0,
2544                         fee_proportional_millionths: 0,
2545                         excess_data: Vec::new()
2546                 });
2547
2548                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2549                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2550                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2551                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2552                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2553
2554                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2555                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2556
2557                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2558                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2559                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2560                         short_channel_id: 333,
2561                         timestamp: 1,
2562                         flags: 0,
2563                         cltv_expiry_delta: (3 << 8) | 1,
2564                         htlc_minimum_msat: 0,
2565                         htlc_maximum_msat: OptionalField::Absent,
2566                         fee_base_msat: 0,
2567                         fee_proportional_millionths: 0,
2568                         excess_data: Vec::new()
2569                 });
2570                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2571                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2572                         short_channel_id: 333,
2573                         timestamp: 1,
2574                         flags: 1,
2575                         cltv_expiry_delta: (3 << 8) | 2,
2576                         htlc_minimum_msat: 0,
2577                         htlc_maximum_msat: OptionalField::Absent,
2578                         fee_base_msat: 100,
2579                         fee_proportional_millionths: 0,
2580                         excess_data: Vec::new()
2581                 });
2582
2583                 {
2584                         // Attempt to route more than available results in a failure.
2585                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2586                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2587                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2588                         } else { panic!(); }
2589                 }
2590
2591                 {
2592                         // Now, attempt to route an exact amount we have should be fine.
2593                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2594                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2595                         assert_eq!(route.paths.len(), 1);
2596                         let path = route.paths.last().unwrap();
2597                         assert_eq!(path.len(), 2);
2598                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2599                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2600                 }
2601
2602                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2603                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2604                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2605                         short_channel_id: 333,
2606                         timestamp: 6,
2607                         flags: 0,
2608                         cltv_expiry_delta: 0,
2609                         htlc_minimum_msat: 0,
2610                         htlc_maximum_msat: OptionalField::Present(10_000),
2611                         fee_base_msat: 0,
2612                         fee_proportional_millionths: 0,
2613                         excess_data: Vec::new()
2614                 });
2615
2616                 {
2617                         // Attempt to route more than available results in a failure.
2618                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2619                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2620                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2621                         } else { panic!(); }
2622                 }
2623
2624                 {
2625                         // Now, attempt to route an exact amount we have should be fine.
2626                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2627                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2628                         assert_eq!(route.paths.len(), 1);
2629                         let path = route.paths.last().unwrap();
2630                         assert_eq!(path.len(), 2);
2631                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2632                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2633                 }
2634         }
2635
2636         #[test]
2637         fn available_liquidity_last_hop_test() {
2638                 // Check that available liquidity properly limits the path even when only
2639                 // one of the latter hops is limited.
2640                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2641                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2642
2643                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2644                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2645                 // Total capacity: 50 sats.
2646
2647                 // Disable other potential paths.
2648                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2649                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2650                         short_channel_id: 2,
2651                         timestamp: 2,
2652                         flags: 2,
2653                         cltv_expiry_delta: 0,
2654                         htlc_minimum_msat: 0,
2655                         htlc_maximum_msat: OptionalField::Present(100_000),
2656                         fee_base_msat: 0,
2657                         fee_proportional_millionths: 0,
2658                         excess_data: Vec::new()
2659                 });
2660                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2661                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2662                         short_channel_id: 7,
2663                         timestamp: 2,
2664                         flags: 2,
2665                         cltv_expiry_delta: 0,
2666                         htlc_minimum_msat: 0,
2667                         htlc_maximum_msat: OptionalField::Present(100_000),
2668                         fee_base_msat: 0,
2669                         fee_proportional_millionths: 0,
2670                         excess_data: Vec::new()
2671                 });
2672
2673                 // Limit capacities
2674
2675                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2676                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2677                         short_channel_id: 12,
2678                         timestamp: 2,
2679                         flags: 0,
2680                         cltv_expiry_delta: 0,
2681                         htlc_minimum_msat: 0,
2682                         htlc_maximum_msat: OptionalField::Present(100_000),
2683                         fee_base_msat: 0,
2684                         fee_proportional_millionths: 0,
2685                         excess_data: Vec::new()
2686                 });
2687                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2688                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2689                         short_channel_id: 13,
2690                         timestamp: 2,
2691                         flags: 0,
2692                         cltv_expiry_delta: 0,
2693                         htlc_minimum_msat: 0,
2694                         htlc_maximum_msat: OptionalField::Present(100_000),
2695                         fee_base_msat: 0,
2696                         fee_proportional_millionths: 0,
2697                         excess_data: Vec::new()
2698                 });
2699
2700                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2701                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2702                         short_channel_id: 6,
2703                         timestamp: 2,
2704                         flags: 0,
2705                         cltv_expiry_delta: 0,
2706                         htlc_minimum_msat: 0,
2707                         htlc_maximum_msat: OptionalField::Present(50_000),
2708                         fee_base_msat: 0,
2709                         fee_proportional_millionths: 0,
2710                         excess_data: Vec::new()
2711                 });
2712                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2713                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2714                         short_channel_id: 11,
2715                         timestamp: 2,
2716                         flags: 0,
2717                         cltv_expiry_delta: 0,
2718                         htlc_minimum_msat: 0,
2719                         htlc_maximum_msat: OptionalField::Present(100_000),
2720                         fee_base_msat: 0,
2721                         fee_proportional_millionths: 0,
2722                         excess_data: Vec::new()
2723                 });
2724                 {
2725                         // Attempt to route more than available results in a failure.
2726                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2727                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2728                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2729                         } else { panic!(); }
2730                 }
2731
2732                 {
2733                         // Now, attempt to route 49 sats (just a bit below the capacity).
2734                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2735                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2736                         assert_eq!(route.paths.len(), 1);
2737                         let mut total_amount_paid_msat = 0;
2738                         for path in &route.paths {
2739                                 assert_eq!(path.len(), 4);
2740                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2741                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2742                         }
2743                         assert_eq!(total_amount_paid_msat, 49_000);
2744                 }
2745
2746                 {
2747                         // Attempt to route an exact amount is also fine
2748                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2749                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2750                         assert_eq!(route.paths.len(), 1);
2751                         let mut total_amount_paid_msat = 0;
2752                         for path in &route.paths {
2753                                 assert_eq!(path.len(), 4);
2754                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2755                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2756                         }
2757                         assert_eq!(total_amount_paid_msat, 50_000);
2758                 }
2759         }
2760
2761         #[test]
2762         fn ignore_fee_first_hop_test() {
2763                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2764                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2765
2766                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2767                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2768                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2769                         short_channel_id: 1,
2770                         timestamp: 2,
2771                         flags: 0,
2772                         cltv_expiry_delta: 0,
2773                         htlc_minimum_msat: 0,
2774                         htlc_maximum_msat: OptionalField::Present(100_000),
2775                         fee_base_msat: 1_000_000,
2776                         fee_proportional_millionths: 0,
2777                         excess_data: Vec::new()
2778                 });
2779                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2780                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2781                         short_channel_id: 3,
2782                         timestamp: 2,
2783                         flags: 0,
2784                         cltv_expiry_delta: 0,
2785                         htlc_minimum_msat: 0,
2786                         htlc_maximum_msat: OptionalField::Present(50_000),
2787                         fee_base_msat: 0,
2788                         fee_proportional_millionths: 0,
2789                         excess_data: Vec::new()
2790                 });
2791
2792                 {
2793                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2794                         assert_eq!(route.paths.len(), 1);
2795                         let mut total_amount_paid_msat = 0;
2796                         for path in &route.paths {
2797                                 assert_eq!(path.len(), 2);
2798                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2799                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2800                         }
2801                         assert_eq!(total_amount_paid_msat, 50_000);
2802                 }
2803         }
2804
2805         #[test]
2806         fn simple_mpp_route_test() {
2807                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2808                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2809
2810                 // We need a route consisting of 3 paths:
2811                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2812                 // To achieve this, the amount being transferred should be around
2813                 // the total capacity of these 3 paths.
2814
2815                 // First, we set limits on these (previously unlimited) channels.
2816                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2817
2818                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2819                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2820                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2821                         short_channel_id: 1,
2822                         timestamp: 2,
2823                         flags: 0,
2824                         cltv_expiry_delta: 0,
2825                         htlc_minimum_msat: 0,
2826                         htlc_maximum_msat: OptionalField::Present(100_000),
2827                         fee_base_msat: 0,
2828                         fee_proportional_millionths: 0,
2829                         excess_data: Vec::new()
2830                 });
2831                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2832                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2833                         short_channel_id: 3,
2834                         timestamp: 2,
2835                         flags: 0,
2836                         cltv_expiry_delta: 0,
2837                         htlc_minimum_msat: 0,
2838                         htlc_maximum_msat: OptionalField::Present(50_000),
2839                         fee_base_msat: 0,
2840                         fee_proportional_millionths: 0,
2841                         excess_data: Vec::new()
2842                 });
2843
2844                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2845                 // (total limit 60).
2846                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2847                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2848                         short_channel_id: 12,
2849                         timestamp: 2,
2850                         flags: 0,
2851                         cltv_expiry_delta: 0,
2852                         htlc_minimum_msat: 0,
2853                         htlc_maximum_msat: OptionalField::Present(60_000),
2854                         fee_base_msat: 0,
2855                         fee_proportional_millionths: 0,
2856                         excess_data: Vec::new()
2857                 });
2858                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2859                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2860                         short_channel_id: 13,
2861                         timestamp: 2,
2862                         flags: 0,
2863                         cltv_expiry_delta: 0,
2864                         htlc_minimum_msat: 0,
2865                         htlc_maximum_msat: OptionalField::Present(60_000),
2866                         fee_base_msat: 0,
2867                         fee_proportional_millionths: 0,
2868                         excess_data: Vec::new()
2869                 });
2870
2871                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2872                 // (total capacity 180 sats).
2873                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2874                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2875                         short_channel_id: 2,
2876                         timestamp: 2,
2877                         flags: 0,
2878                         cltv_expiry_delta: 0,
2879                         htlc_minimum_msat: 0,
2880                         htlc_maximum_msat: OptionalField::Present(200_000),
2881                         fee_base_msat: 0,
2882                         fee_proportional_millionths: 0,
2883                         excess_data: Vec::new()
2884                 });
2885                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2886                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2887                         short_channel_id: 4,
2888                         timestamp: 2,
2889                         flags: 0,
2890                         cltv_expiry_delta: 0,
2891                         htlc_minimum_msat: 0,
2892                         htlc_maximum_msat: OptionalField::Present(180_000),
2893                         fee_base_msat: 0,
2894                         fee_proportional_millionths: 0,
2895                         excess_data: Vec::new()
2896                 });
2897
2898                 {
2899                         // Attempt to route more than available results in a failure.
2900                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2901                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2902                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2903                         } else { panic!(); }
2904                 }
2905
2906                 {
2907                         // Now, attempt to route 250 sats (just a bit below the capacity).
2908                         // Our algorithm should provide us with these 3 paths.
2909                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2910                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2911                         assert_eq!(route.paths.len(), 3);
2912                         let mut total_amount_paid_msat = 0;
2913                         for path in &route.paths {
2914                                 assert_eq!(path.len(), 2);
2915                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2916                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2917                         }
2918                         assert_eq!(total_amount_paid_msat, 250_000);
2919                 }
2920
2921                 {
2922                         // Attempt to route an exact amount is also fine
2923                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2924                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2925                         assert_eq!(route.paths.len(), 3);
2926                         let mut total_amount_paid_msat = 0;
2927                         for path in &route.paths {
2928                                 assert_eq!(path.len(), 2);
2929                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2930                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2931                         }
2932                         assert_eq!(total_amount_paid_msat, 290_000);
2933                 }
2934         }
2935
2936         #[test]
2937         fn long_mpp_route_test() {
2938                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2939                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2940
2941                 // We need a route consisting of 3 paths:
2942                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2943                 // Note that these paths overlap (channels 5, 12, 13).
2944                 // We will route 300 sats.
2945                 // Each path will have 100 sats capacity, those channels which
2946                 // are used twice will have 200 sats capacity.
2947
2948                 // Disable other potential paths.
2949                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2950                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2951                         short_channel_id: 2,
2952                         timestamp: 2,
2953                         flags: 2,
2954                         cltv_expiry_delta: 0,
2955                         htlc_minimum_msat: 0,
2956                         htlc_maximum_msat: OptionalField::Present(100_000),
2957                         fee_base_msat: 0,
2958                         fee_proportional_millionths: 0,
2959                         excess_data: Vec::new()
2960                 });
2961                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2962                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2963                         short_channel_id: 7,
2964                         timestamp: 2,
2965                         flags: 2,
2966                         cltv_expiry_delta: 0,
2967                         htlc_minimum_msat: 0,
2968                         htlc_maximum_msat: OptionalField::Present(100_000),
2969                         fee_base_msat: 0,
2970                         fee_proportional_millionths: 0,
2971                         excess_data: Vec::new()
2972                 });
2973
2974                 // Path via {node0, node2} is channels {1, 3, 5}.
2975                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2976                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2977                         short_channel_id: 1,
2978                         timestamp: 2,
2979                         flags: 0,
2980                         cltv_expiry_delta: 0,
2981                         htlc_minimum_msat: 0,
2982                         htlc_maximum_msat: OptionalField::Present(100_000),
2983                         fee_base_msat: 0,
2984                         fee_proportional_millionths: 0,
2985                         excess_data: Vec::new()
2986                 });
2987                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2988                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2989                         short_channel_id: 3,
2990                         timestamp: 2,
2991                         flags: 0,
2992                         cltv_expiry_delta: 0,
2993                         htlc_minimum_msat: 0,
2994                         htlc_maximum_msat: OptionalField::Present(100_000),
2995                         fee_base_msat: 0,
2996                         fee_proportional_millionths: 0,
2997                         excess_data: Vec::new()
2998                 });
2999
3000                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3001                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3002                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3003                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3004                         short_channel_id: 5,
3005                         timestamp: 2,
3006                         flags: 0,
3007                         cltv_expiry_delta: 0,
3008                         htlc_minimum_msat: 0,
3009                         htlc_maximum_msat: OptionalField::Present(200_000),
3010                         fee_base_msat: 0,
3011                         fee_proportional_millionths: 0,
3012                         excess_data: Vec::new()
3013                 });
3014
3015                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3016                 // Add 100 sats to the capacities of {12, 13}, because these channels
3017                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3018                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3019                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3020                         short_channel_id: 12,
3021                         timestamp: 2,
3022                         flags: 0,
3023                         cltv_expiry_delta: 0,
3024                         htlc_minimum_msat: 0,
3025                         htlc_maximum_msat: OptionalField::Present(200_000),
3026                         fee_base_msat: 0,
3027                         fee_proportional_millionths: 0,
3028                         excess_data: Vec::new()
3029                 });
3030                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3031                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3032                         short_channel_id: 13,
3033                         timestamp: 2,
3034                         flags: 0,
3035                         cltv_expiry_delta: 0,
3036                         htlc_minimum_msat: 0,
3037                         htlc_maximum_msat: OptionalField::Present(200_000),
3038                         fee_base_msat: 0,
3039                         fee_proportional_millionths: 0,
3040                         excess_data: Vec::new()
3041                 });
3042
3043                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3044                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3045                         short_channel_id: 6,
3046                         timestamp: 2,
3047                         flags: 0,
3048                         cltv_expiry_delta: 0,
3049                         htlc_minimum_msat: 0,
3050                         htlc_maximum_msat: OptionalField::Present(100_000),
3051                         fee_base_msat: 0,
3052                         fee_proportional_millionths: 0,
3053                         excess_data: Vec::new()
3054                 });
3055                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3056                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3057                         short_channel_id: 11,
3058                         timestamp: 2,
3059                         flags: 0,
3060                         cltv_expiry_delta: 0,
3061                         htlc_minimum_msat: 0,
3062                         htlc_maximum_msat: OptionalField::Present(100_000),
3063                         fee_base_msat: 0,
3064                         fee_proportional_millionths: 0,
3065                         excess_data: Vec::new()
3066                 });
3067
3068                 // Path via {node7, node2} is channels {12, 13, 5}.
3069                 // We already limited them to 200 sats (they are used twice for 100 sats).
3070                 // Nothing to do here.
3071
3072                 {
3073                         // Attempt to route more than available results in a failure.
3074                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3075                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3076                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3077                         } else { panic!(); }
3078                 }
3079
3080                 {
3081                         // Now, attempt to route 300 sats (exact amount we can route).
3082                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3083                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3084                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3085                         assert_eq!(route.paths.len(), 3);
3086
3087                         let mut total_amount_paid_msat = 0;
3088                         for path in &route.paths {
3089                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3090                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3091                         }
3092                         assert_eq!(total_amount_paid_msat, 300_000);
3093                 }
3094
3095         }
3096
3097         #[test]
3098         fn mpp_cheaper_route_test() {
3099                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3100                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3101
3102                 // This test checks that if we have two cheaper paths and one more expensive path,
3103                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3104                 // two cheaper paths will be taken.
3105                 // These paths have equal available liquidity.
3106
3107                 // We need a combination of 3 paths:
3108                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3109                 // Note that these paths overlap (channels 5, 12, 13).
3110                 // Each path will have 100 sats capacity, those channels which
3111                 // are used twice will have 200 sats capacity.
3112
3113                 // Disable other potential paths.
3114                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3115                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3116                         short_channel_id: 2,
3117                         timestamp: 2,
3118                         flags: 2,
3119                         cltv_expiry_delta: 0,
3120                         htlc_minimum_msat: 0,
3121                         htlc_maximum_msat: OptionalField::Present(100_000),
3122                         fee_base_msat: 0,
3123                         fee_proportional_millionths: 0,
3124                         excess_data: Vec::new()
3125                 });
3126                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3127                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3128                         short_channel_id: 7,
3129                         timestamp: 2,
3130                         flags: 2,
3131                         cltv_expiry_delta: 0,
3132                         htlc_minimum_msat: 0,
3133                         htlc_maximum_msat: OptionalField::Present(100_000),
3134                         fee_base_msat: 0,
3135                         fee_proportional_millionths: 0,
3136                         excess_data: Vec::new()
3137                 });
3138
3139                 // Path via {node0, node2} is channels {1, 3, 5}.
3140                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3141                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3142                         short_channel_id: 1,
3143                         timestamp: 2,
3144                         flags: 0,
3145                         cltv_expiry_delta: 0,
3146                         htlc_minimum_msat: 0,
3147                         htlc_maximum_msat: OptionalField::Present(100_000),
3148                         fee_base_msat: 0,
3149                         fee_proportional_millionths: 0,
3150                         excess_data: Vec::new()
3151                 });
3152                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3153                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3154                         short_channel_id: 3,
3155                         timestamp: 2,
3156                         flags: 0,
3157                         cltv_expiry_delta: 0,
3158                         htlc_minimum_msat: 0,
3159                         htlc_maximum_msat: OptionalField::Present(100_000),
3160                         fee_base_msat: 0,
3161                         fee_proportional_millionths: 0,
3162                         excess_data: Vec::new()
3163                 });
3164
3165                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3166                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3167                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3168                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3169                         short_channel_id: 5,
3170                         timestamp: 2,
3171                         flags: 0,
3172                         cltv_expiry_delta: 0,
3173                         htlc_minimum_msat: 0,
3174                         htlc_maximum_msat: OptionalField::Present(200_000),
3175                         fee_base_msat: 0,
3176                         fee_proportional_millionths: 0,
3177                         excess_data: Vec::new()
3178                 });
3179
3180                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3181                 // Add 100 sats to the capacities of {12, 13}, because these channels
3182                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3183                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3184                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3185                         short_channel_id: 12,
3186                         timestamp: 2,
3187                         flags: 0,
3188                         cltv_expiry_delta: 0,
3189                         htlc_minimum_msat: 0,
3190                         htlc_maximum_msat: OptionalField::Present(200_000),
3191                         fee_base_msat: 0,
3192                         fee_proportional_millionths: 0,
3193                         excess_data: Vec::new()
3194                 });
3195                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3196                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3197                         short_channel_id: 13,
3198                         timestamp: 2,
3199                         flags: 0,
3200                         cltv_expiry_delta: 0,
3201                         htlc_minimum_msat: 0,
3202                         htlc_maximum_msat: OptionalField::Present(200_000),
3203                         fee_base_msat: 0,
3204                         fee_proportional_millionths: 0,
3205                         excess_data: Vec::new()
3206                 });
3207
3208                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3209                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3210                         short_channel_id: 6,
3211                         timestamp: 2,
3212                         flags: 0,
3213                         cltv_expiry_delta: 0,
3214                         htlc_minimum_msat: 0,
3215                         htlc_maximum_msat: OptionalField::Present(100_000),
3216                         fee_base_msat: 1_000,
3217                         fee_proportional_millionths: 0,
3218                         excess_data: Vec::new()
3219                 });
3220                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3221                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3222                         short_channel_id: 11,
3223                         timestamp: 2,
3224                         flags: 0,
3225                         cltv_expiry_delta: 0,
3226                         htlc_minimum_msat: 0,
3227                         htlc_maximum_msat: OptionalField::Present(100_000),
3228                         fee_base_msat: 0,
3229                         fee_proportional_millionths: 0,
3230                         excess_data: Vec::new()
3231                 });
3232
3233                 // Path via {node7, node2} is channels {12, 13, 5}.
3234                 // We already limited them to 200 sats (they are used twice for 100 sats).
3235                 // Nothing to do here.
3236
3237                 {
3238                         // Now, attempt to route 180 sats.
3239                         // Our algorithm should provide us with these 2 paths.
3240                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3241                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3242                         assert_eq!(route.paths.len(), 2);
3243
3244                         let mut total_value_transferred_msat = 0;
3245                         let mut total_paid_msat = 0;
3246                         for path in &route.paths {
3247                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3248                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3249                                 for hop in path {
3250                                         total_paid_msat += hop.fee_msat;
3251                                 }
3252                         }
3253                         // If we paid fee, this would be higher.
3254                         assert_eq!(total_value_transferred_msat, 180_000);
3255                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3256                         assert_eq!(total_fees_paid, 0);
3257                 }
3258         }
3259
3260         #[test]
3261         fn fees_on_mpp_route_test() {
3262                 // This test makes sure that MPP algorithm properly takes into account
3263                 // fees charged on the channels, by making the fees impactful:
3264                 // if the fee is not properly accounted for, the behavior is different.
3265                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3266                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3267
3268                 // We need a route consisting of 2 paths:
3269                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3270                 // We will route 200 sats, Each path will have 100 sats capacity.
3271
3272                 // This test is not particularly stable: e.g.,
3273                 // there's a way to route via {node0, node2, node4}.
3274                 // It works while pathfinding is deterministic, but can be broken otherwise.
3275                 // It's fine to ignore this concern for now.
3276
3277                 // Disable other potential paths.
3278                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3279                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3280                         short_channel_id: 2,
3281                         timestamp: 2,
3282                         flags: 2,
3283                         cltv_expiry_delta: 0,
3284                         htlc_minimum_msat: 0,
3285                         htlc_maximum_msat: OptionalField::Present(100_000),
3286                         fee_base_msat: 0,
3287                         fee_proportional_millionths: 0,
3288                         excess_data: Vec::new()
3289                 });
3290
3291                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3292                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3293                         short_channel_id: 7,
3294                         timestamp: 2,
3295                         flags: 2,
3296                         cltv_expiry_delta: 0,
3297                         htlc_minimum_msat: 0,
3298                         htlc_maximum_msat: OptionalField::Present(100_000),
3299                         fee_base_msat: 0,
3300                         fee_proportional_millionths: 0,
3301                         excess_data: Vec::new()
3302                 });
3303
3304                 // Path via {node0, node2} is channels {1, 3, 5}.
3305                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3306                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3307                         short_channel_id: 1,
3308                         timestamp: 2,
3309                         flags: 0,
3310                         cltv_expiry_delta: 0,
3311                         htlc_minimum_msat: 0,
3312                         htlc_maximum_msat: OptionalField::Present(100_000),
3313                         fee_base_msat: 0,
3314                         fee_proportional_millionths: 0,
3315                         excess_data: Vec::new()
3316                 });
3317                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3318                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3319                         short_channel_id: 3,
3320                         timestamp: 2,
3321                         flags: 0,
3322                         cltv_expiry_delta: 0,
3323                         htlc_minimum_msat: 0,
3324                         htlc_maximum_msat: OptionalField::Present(100_000),
3325                         fee_base_msat: 0,
3326                         fee_proportional_millionths: 0,
3327                         excess_data: Vec::new()
3328                 });
3329
3330                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3331                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3332                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3333                         short_channel_id: 5,
3334                         timestamp: 2,
3335                         flags: 0,
3336                         cltv_expiry_delta: 0,
3337                         htlc_minimum_msat: 0,
3338                         htlc_maximum_msat: OptionalField::Present(100_000),
3339                         fee_base_msat: 0,
3340                         fee_proportional_millionths: 0,
3341                         excess_data: Vec::new()
3342                 });
3343
3344                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3345                 // All channels should be 100 sats capacity. But for the fee experiment,
3346                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3347                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3348                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3349                 // so no matter how large are other channels,
3350                 // the whole path will be limited by 100 sats with just these 2 conditions:
3351                 // - channel 12 capacity is 250 sats
3352                 // - fee for channel 6 is 150 sats
3353                 // Let's test this by enforcing these 2 conditions and removing other limits.
3354                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3355                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3356                         short_channel_id: 12,
3357                         timestamp: 2,
3358                         flags: 0,
3359                         cltv_expiry_delta: 0,
3360                         htlc_minimum_msat: 0,
3361                         htlc_maximum_msat: OptionalField::Present(250_000),
3362                         fee_base_msat: 0,
3363                         fee_proportional_millionths: 0,
3364                         excess_data: Vec::new()
3365                 });
3366                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3367                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3368                         short_channel_id: 13,
3369                         timestamp: 2,
3370                         flags: 0,
3371                         cltv_expiry_delta: 0,
3372                         htlc_minimum_msat: 0,
3373                         htlc_maximum_msat: OptionalField::Absent,
3374                         fee_base_msat: 0,
3375                         fee_proportional_millionths: 0,
3376                         excess_data: Vec::new()
3377                 });
3378
3379                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3380                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3381                         short_channel_id: 6,
3382                         timestamp: 2,
3383                         flags: 0,
3384                         cltv_expiry_delta: 0,
3385                         htlc_minimum_msat: 0,
3386                         htlc_maximum_msat: OptionalField::Absent,
3387                         fee_base_msat: 150_000,
3388                         fee_proportional_millionths: 0,
3389                         excess_data: Vec::new()
3390                 });
3391                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3392                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3393                         short_channel_id: 11,
3394                         timestamp: 2,
3395                         flags: 0,
3396                         cltv_expiry_delta: 0,
3397                         htlc_minimum_msat: 0,
3398                         htlc_maximum_msat: OptionalField::Absent,
3399                         fee_base_msat: 0,
3400                         fee_proportional_millionths: 0,
3401                         excess_data: Vec::new()
3402                 });
3403
3404                 {
3405                         // Attempt to route more than available results in a failure.
3406                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3407                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3408                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3409                         } else { panic!(); }
3410                 }
3411
3412                 {
3413                         // Now, attempt to route 200 sats (exact amount we can route).
3414                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3415                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3416                         assert_eq!(route.paths.len(), 2);
3417
3418                         let mut total_amount_paid_msat = 0;
3419                         for path in &route.paths {
3420                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3421                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3422                         }
3423                         assert_eq!(total_amount_paid_msat, 200_000);
3424                 }
3425
3426         }
3427
3428         #[test]
3429         fn drop_lowest_channel_mpp_route_test() {
3430                 // This test checks that low-capacity channel is dropped when after
3431                 // path finding we realize that we found more capacity than we need.
3432                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3433                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3434
3435                 // We need a route consisting of 3 paths:
3436                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3437
3438                 // The first and the second paths should be sufficient, but the third should be
3439                 // cheaper, so that we select it but drop later.
3440
3441                 // First, we set limits on these (previously unlimited) channels.
3442                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3443
3444                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3445                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3446                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3447                         short_channel_id: 1,
3448                         timestamp: 2,
3449                         flags: 0,
3450                         cltv_expiry_delta: 0,
3451                         htlc_minimum_msat: 0,
3452                         htlc_maximum_msat: OptionalField::Present(100_000),
3453                         fee_base_msat: 0,
3454                         fee_proportional_millionths: 0,
3455                         excess_data: Vec::new()
3456                 });
3457                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3458                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3459                         short_channel_id: 3,
3460                         timestamp: 2,
3461                         flags: 0,
3462                         cltv_expiry_delta: 0,
3463                         htlc_minimum_msat: 0,
3464                         htlc_maximum_msat: OptionalField::Present(50_000),
3465                         fee_base_msat: 100,
3466                         fee_proportional_millionths: 0,
3467                         excess_data: Vec::new()
3468                 });
3469
3470                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3471                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3472                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3473                         short_channel_id: 12,
3474                         timestamp: 2,
3475                         flags: 0,
3476                         cltv_expiry_delta: 0,
3477                         htlc_minimum_msat: 0,
3478                         htlc_maximum_msat: OptionalField::Present(60_000),
3479                         fee_base_msat: 100,
3480                         fee_proportional_millionths: 0,
3481                         excess_data: Vec::new()
3482                 });
3483                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3484                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3485                         short_channel_id: 13,
3486                         timestamp: 2,
3487                         flags: 0,
3488                         cltv_expiry_delta: 0,
3489                         htlc_minimum_msat: 0,
3490                         htlc_maximum_msat: OptionalField::Present(60_000),
3491                         fee_base_msat: 0,
3492                         fee_proportional_millionths: 0,
3493                         excess_data: Vec::new()
3494                 });
3495
3496                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3497                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3498                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3499                         short_channel_id: 2,
3500                         timestamp: 2,
3501                         flags: 0,
3502                         cltv_expiry_delta: 0,
3503                         htlc_minimum_msat: 0,
3504                         htlc_maximum_msat: OptionalField::Present(20_000),
3505                         fee_base_msat: 0,
3506                         fee_proportional_millionths: 0,
3507                         excess_data: Vec::new()
3508                 });
3509                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3510                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3511                         short_channel_id: 4,
3512                         timestamp: 2,
3513                         flags: 0,
3514                         cltv_expiry_delta: 0,
3515                         htlc_minimum_msat: 0,
3516                         htlc_maximum_msat: OptionalField::Present(20_000),
3517                         fee_base_msat: 0,
3518                         fee_proportional_millionths: 0,
3519                         excess_data: Vec::new()
3520                 });
3521
3522                 {
3523                         // Attempt to route more than available results in a failure.
3524                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3525                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3526                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3527                         } else { panic!(); }
3528                 }
3529
3530                 {
3531                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3532                         // Our algorithm should provide us with these 3 paths.
3533                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3534                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3535                         assert_eq!(route.paths.len(), 3);
3536                         let mut total_amount_paid_msat = 0;
3537                         for path in &route.paths {
3538                                 assert_eq!(path.len(), 2);
3539                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3540                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3541                         }
3542                         assert_eq!(total_amount_paid_msat, 125_000);
3543                 }
3544
3545                 {
3546                         // Attempt to route without the last small cheap channel
3547                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3548                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3549                         assert_eq!(route.paths.len(), 2);
3550                         let mut total_amount_paid_msat = 0;
3551                         for path in &route.paths {
3552                                 assert_eq!(path.len(), 2);
3553                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3554                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3555                         }
3556                         assert_eq!(total_amount_paid_msat, 90_000);
3557                 }
3558         }
3559
3560         #[test]
3561         fn min_criteria_consistency() {
3562                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3563                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3564                 // was updated with a different criterion from the heap sorting, resulting in loops in
3565                 // calculated paths. We test for that specific case here.
3566
3567                 // We construct a network that looks like this:
3568                 //
3569                 //            node2 -1(3)2- node3
3570                 //              2          2
3571                 //               (2)     (4)
3572                 //                  1   1
3573                 //    node1 -1(5)2- node4 -1(1)2- node6
3574                 //    2
3575                 //   (6)
3576                 //        1
3577                 // our_node
3578                 //
3579                 // We create a loop on the side of our real path - our destination is node 6, with a
3580                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3581                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3582                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3583                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3584                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3585                 // "previous hop" being set to node 3, creating a loop in the path.
3586                 let secp_ctx = Secp256k1::new();
3587                 let logger = Arc::new(test_utils::TestLogger::new());
3588                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3589                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3590
3591                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3592                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3593                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3594                         short_channel_id: 6,
3595                         timestamp: 1,
3596                         flags: 0,
3597                         cltv_expiry_delta: (6 << 8) | 0,
3598                         htlc_minimum_msat: 0,
3599                         htlc_maximum_msat: OptionalField::Absent,
3600                         fee_base_msat: 0,
3601                         fee_proportional_millionths: 0,
3602                         excess_data: Vec::new()
3603                 });
3604                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3605
3606                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3607                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3608                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3609                         short_channel_id: 5,
3610                         timestamp: 1,
3611                         flags: 0,
3612                         cltv_expiry_delta: (5 << 8) | 0,
3613                         htlc_minimum_msat: 0,
3614                         htlc_maximum_msat: OptionalField::Absent,
3615                         fee_base_msat: 100,
3616                         fee_proportional_millionths: 0,
3617                         excess_data: Vec::new()
3618                 });
3619                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3620
3621                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3622                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3623                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3624                         short_channel_id: 4,
3625                         timestamp: 1,
3626                         flags: 0,
3627                         cltv_expiry_delta: (4 << 8) | 0,
3628                         htlc_minimum_msat: 0,
3629                         htlc_maximum_msat: OptionalField::Absent,
3630                         fee_base_msat: 0,
3631                         fee_proportional_millionths: 0,
3632                         excess_data: Vec::new()
3633                 });
3634                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3635
3636                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3637                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3639                         short_channel_id: 3,
3640                         timestamp: 1,
3641                         flags: 0,
3642                         cltv_expiry_delta: (3 << 8) | 0,
3643                         htlc_minimum_msat: 0,
3644                         htlc_maximum_msat: OptionalField::Absent,
3645                         fee_base_msat: 0,
3646                         fee_proportional_millionths: 0,
3647                         excess_data: Vec::new()
3648                 });
3649                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3650
3651                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3652                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3653                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3654                         short_channel_id: 2,
3655                         timestamp: 1,
3656                         flags: 0,
3657                         cltv_expiry_delta: (2 << 8) | 0,
3658                         htlc_minimum_msat: 0,
3659                         htlc_maximum_msat: OptionalField::Absent,
3660                         fee_base_msat: 0,
3661                         fee_proportional_millionths: 0,
3662                         excess_data: Vec::new()
3663                 });
3664
3665                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3666                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3667                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3668                         short_channel_id: 1,
3669                         timestamp: 1,
3670                         flags: 0,
3671                         cltv_expiry_delta: (1 << 8) | 0,
3672                         htlc_minimum_msat: 100,
3673                         htlc_maximum_msat: OptionalField::Absent,
3674                         fee_base_msat: 0,
3675                         fee_proportional_millionths: 0,
3676                         excess_data: Vec::new()
3677                 });
3678                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3679
3680                 {
3681                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3682                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3683                         assert_eq!(route.paths.len(), 1);
3684                         assert_eq!(route.paths[0].len(), 3);
3685
3686                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3687                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3688                         assert_eq!(route.paths[0][0].fee_msat, 100);
3689                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3690                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3691                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3692
3693                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3694                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3695                         assert_eq!(route.paths[0][1].fee_msat, 0);
3696                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3697                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3698                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3699
3700                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3701                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3702                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3703                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3704                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3705                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3706                 }
3707         }
3708
3709
3710         #[test]
3711         fn exact_fee_liquidity_limit() {
3712                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3713                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3714                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3715                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3716                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
3717
3718                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3719                 // send.
3720                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3721                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3722                         short_channel_id: 2,
3723                         timestamp: 2,
3724                         flags: 0,
3725                         cltv_expiry_delta: 0,
3726                         htlc_minimum_msat: 0,
3727                         htlc_maximum_msat: OptionalField::Present(85_000),
3728                         fee_base_msat: 0,
3729                         fee_proportional_millionths: 0,
3730                         excess_data: Vec::new()
3731                 });
3732
3733                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3734                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3735                         short_channel_id: 12,
3736                         timestamp: 2,
3737                         flags: 0,
3738                         cltv_expiry_delta: (4 << 8) | 1,
3739                         htlc_minimum_msat: 0,
3740                         htlc_maximum_msat: OptionalField::Present(270_000),
3741                         fee_base_msat: 0,
3742                         fee_proportional_millionths: 1000000,
3743                         excess_data: Vec::new()
3744                 });
3745
3746                 {
3747                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
3748                         // 200% fee charged channel 13 in the 1-to-2 direction.
3749                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3750                         assert_eq!(route.paths.len(), 1);
3751                         assert_eq!(route.paths[0].len(), 2);
3752
3753                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3754                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3755                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3756                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3757                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3758                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3759
3760                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3761                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3762                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3763                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3764                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3765                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3766                 }
3767         }
3768
3769         #[test]
3770         fn htlc_max_reduction_below_min() {
3771                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3772                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3773                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3774                 // resulting in us thinking there is no possible path, even if other paths exist.
3775                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3776                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3777
3778                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3779                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
3780                 // then try to send 90_000.
3781                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3782                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3783                         short_channel_id: 2,
3784                         timestamp: 2,
3785                         flags: 0,
3786                         cltv_expiry_delta: 0,
3787                         htlc_minimum_msat: 0,
3788                         htlc_maximum_msat: OptionalField::Present(80_000),
3789                         fee_base_msat: 0,
3790                         fee_proportional_millionths: 0,
3791                         excess_data: Vec::new()
3792                 });
3793                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3794                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3795                         short_channel_id: 4,
3796                         timestamp: 2,
3797                         flags: 0,
3798                         cltv_expiry_delta: (4 << 8) | 1,
3799                         htlc_minimum_msat: 90_000,
3800                         htlc_maximum_msat: OptionalField::Absent,
3801                         fee_base_msat: 0,
3802                         fee_proportional_millionths: 0,
3803                         excess_data: Vec::new()
3804                 });
3805
3806                 {
3807                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
3808                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
3809                         // expensive) channels 12-13 path.
3810                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3811                         assert_eq!(route.paths.len(), 1);
3812                         assert_eq!(route.paths[0].len(), 2);
3813
3814                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3815                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3816                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3817                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3818                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3819                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3820
3821                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3822                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3823                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3824                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3825                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3826                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3827                 }
3828         }
3829
3830         use std::fs::File;
3831         use util::ser::Readable;
3832         /// Tries to open a network graph file, or panics with a URL to fetch it.
3833         pub(super) fn get_route_file() -> Result<std::fs::File, std::io::Error> {
3834                 let res = File::open("net_graph-2021-02-12.bin") // By default we're run in RL/lightning
3835                         .or_else(|_| File::open("lightning/net_graph-2021-02-12.bin")) // We may be run manually in RL/
3836                         .or_else(|_| { // Fall back to guessing based on the binary location
3837                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3838                                 let mut path = std::env::current_exe().unwrap();
3839                                 path.pop(); // lightning-...
3840                                 path.pop(); // deps
3841                                 path.pop(); // debug
3842                                 path.pop(); // target
3843                                 path.push("lightning");
3844                                 path.push("net_graph-2021-02-12.bin");
3845                                 eprintln!("{}", path.to_str().unwrap());
3846                                 File::open(path)
3847                         });
3848                 #[cfg(require_route_graph_test)]
3849                 return Ok(res.expect("Didn't have route graph and was configured to require it"));
3850                 res
3851         }
3852
3853         pub(super) fn random_init_seed() -> u64 {
3854                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3855                 use std::hash::{BuildHasher, Hasher};
3856                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3857                 println!("Using seed of {}", seed);
3858                 seed
3859         }
3860
3861         #[test]
3862         fn generate_routes() {
3863                 let mut d = match get_route_file() {
3864                         Ok(f) => f,
3865                         Err(_) => {
3866                                 eprintln!("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3867                                 return;
3868                         },
3869                 };
3870                 let graph = NetworkGraph::read(&mut d).unwrap();
3871
3872                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3873                 let mut seed = random_init_seed() as usize;
3874                 'load_endpoints: for _ in 0..10 {
3875                         loop {
3876                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3877                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3878                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3879                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3880                                 let amt = seed as u64 % 200_000_000;
3881                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3882                                         continue 'load_endpoints;
3883                                 }
3884                         }
3885                 }
3886         }
3887
3888         #[test]
3889         fn generate_routes_mpp() {
3890                 let mut d = match get_route_file() {
3891                         Ok(f) => f,
3892                         Err(_) => {
3893                                 eprintln!("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3894                                 return;
3895                         },
3896                 };
3897                 let graph = NetworkGraph::read(&mut d).unwrap();
3898
3899                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3900                 let mut seed = random_init_seed() as usize;
3901                 'load_endpoints: for _ in 0..10 {
3902                         loop {
3903                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3904                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3905                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3906                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3907                                 let amt = seed as u64 % 200_000_000;
3908                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3909                                         continue 'load_endpoints;
3910                                 }
3911                         }
3912                 }
3913         }
3914 }
3915
3916 #[cfg(all(test, feature = "unstable"))]
3917 mod benches {
3918         use super::*;
3919         use util::logger::{Logger, Record};
3920
3921         use std::fs::File;
3922         use test::Bencher;
3923
3924         struct DummyLogger {}
3925         impl Logger for DummyLogger {
3926                 fn log(&self, _record: &Record) {}
3927         }
3928
3929         #[bench]
3930         fn generate_routes(bench: &mut Bencher) {
3931                 let mut d = tests::get_route_file()
3932                         .expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3933                 let graph = NetworkGraph::read(&mut d).unwrap();
3934
3935                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3936                 let mut path_endpoints = Vec::new();
3937                 let mut seed: usize = 0xdeadbeef;
3938                 'load_endpoints: for _ in 0..100 {
3939                         loop {
3940                                 seed *= 0xdeadbeef;
3941                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3942                                 seed *= 0xdeadbeef;
3943                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3944                                 let amt = seed as u64 % 1_000_000;
3945                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3946                                         path_endpoints.push((src, dst, amt));
3947                                         continue 'load_endpoints;
3948                                 }
3949                         }
3950                 }
3951
3952                 // ...then benchmark finding paths between the nodes we learned.
3953                 let mut idx = 0;
3954                 bench.iter(|| {
3955                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3956                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3957                         idx += 1;
3958                 });
3959         }
3960
3961         #[bench]
3962         fn generate_mpp_routes(bench: &mut Bencher) {
3963                 let mut d = tests::get_route_file()
3964                         .expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3965                 let graph = NetworkGraph::read(&mut d).unwrap();
3966
3967                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3968                 let mut path_endpoints = Vec::new();
3969                 let mut seed: usize = 0xdeadbeef;
3970                 'load_endpoints: for _ in 0..100 {
3971                         loop {
3972                                 seed *= 0xdeadbeef;
3973                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3974                                 seed *= 0xdeadbeef;
3975                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3976                                 let amt = seed as u64 % 1_000_000;
3977                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3978                                         path_endpoints.push((src, dst, amt));
3979                                         continue 'load_endpoints;
3980                                 }
3981                         }
3982                 }
3983
3984                 // ...then benchmark finding paths between the nodes we learned.
3985                 let mut idx = 0;
3986                 bench.iter(|| {
3987                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3988                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
3989                         idx += 1;
3990                 });
3991         }
3992 }